WO2023181659A1 - Particles, method for manufacturing particles, method for manufacturing negative electrode, and method for manufacturing secondary battery - Google Patents

Particles, method for manufacturing particles, method for manufacturing negative electrode, and method for manufacturing secondary battery Download PDF

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WO2023181659A1
WO2023181659A1 PCT/JP2023/003531 JP2023003531W WO2023181659A1 WO 2023181659 A1 WO2023181659 A1 WO 2023181659A1 JP 2023003531 W JP2023003531 W JP 2023003531W WO 2023181659 A1 WO2023181659 A1 WO 2023181659A1
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Prior art keywords
particles
graphite
mass
less
cerium
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PCT/JP2023/003531
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French (fr)
Japanese (ja)
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佑介 杉山
貴大 中西
直人 丸
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三菱ケミカル株式会社
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Publication of WO2023181659A1 publication Critical patent/WO2023181659A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals

Definitions

  • the present invention relates to particles, a method for producing particles, a method for producing a negative electrode, and a method for producing a secondary battery.
  • lithium ion secondary batteries are attracting attention because of their higher energy density and superior charging and discharging characteristics compared to nickel-cadmium batteries and nickel-hydrogen batteries.
  • a lithium ion secondary battery a nonaqueous lithium secondary battery consisting of a positive electrode and a negative electrode that can absorb and release lithium ions, and a nonaqueous electrolyte in which lithium salts such as LiPF 6 and LiBF 4 are dissolved has been developed and put into practical use. has been done.
  • Patent Document 1 proposes a negative electrode material of composite graphite particles containing silicon particles.
  • the silicon particles are not coated or otherwise treated, and a side reaction with the electrolyte occurs, so that the cycle characteristics of the secondary battery cannot be said to be sufficient.
  • various types of negative electrode materials have been studied in the past, but no negative electrode material has been found that can sufficiently improve the cycle characteristics of secondary batteries.
  • An object of the present invention is to provide particles that can provide excellent cycle characteristics as a negative material for secondary batteries. Another object of the present invention is to provide a method for producing particles for obtaining the particles.
  • the present inventors have developed particles in which particles (B) containing tantalum oxide and/or cerium compound are encapsulated in graphite, or particles (B1) in which the surface of particles (B1) containing silicon element is coated with a cerium compound. ) was found to improve the cycle characteristics of a secondary battery, leading to the present invention.
  • the gist of the present invention is as follows. [1] Particles containing graphite (A) and particles (B) containing at least one selected from the group consisting of tantalum compounds and cerium compounds, wherein the particles (B) are encapsulated in the graphite (A). Particles. [2] The particles according to [1], wherein the graphite (A) has a Raman R value of 0.1 to 0.7. [3] The particle according to [1] or [2], wherein the particle (B) further contains silicon element.
  • [8] The particle according to any one of [1] to [7], which has a carbonaceous substance on the surface.
  • a method for producing a negative electrode comprising a step of applying particles according to any one of [1] to [9] and [13] to [14] on a current collector.
  • the particles of the present invention as an active material for a negative electrode of a secondary battery, it is possible to provide a secondary battery with excellent cycle characteristics. According to the method for producing particles of the present invention, such particles can be produced.
  • the particles of the present invention are particles (B) containing graphite (A) and at least one selected from the group consisting of tantalum compounds and cerium compounds (hereinafter simply referred to as "particles (B)"). ), in which the particle (B) is encapsulated in graphite (A).
  • the particle of the present invention is a particle containing a particle (B) containing a cerium compound, in which the surface of the particle (B1) containing a silicon element is coated with a cerium compound. .
  • second particles of the present invention Since the particles (B) are encapsulated in the graphite (A) or the surfaces of the particles (B1) containing silicon element are coated with a cerium compound, the stability against the electrolyte is improved. The cycle characteristics of the next battery can be improved.
  • the following description of the particles (B1) containing the silicon element and the cerium compound in the particles of the present invention applies similarly.
  • the second particle of the present invention is an embodiment of the particle (B) in the particles of the present invention described below, the following description applies similarly.
  • the particles of the present invention may include graphite (A) and particles whose surfaces are coated with a cerium compound, particles (B1) containing silicon element, which are the second particles of the present invention.
  • this particle may be referred to as "the third particle of the present invention". Since the third particle of the present invention is one embodiment of the particle of the present invention, the following description applies similarly.
  • graphite (A) As the graphite (A), either natural graphite or artificial graphite may be used, but natural graphite is preferable because it has a high capacity.
  • Graphite (A) preferably has few impurities, and is preferably used after being subjected to a purification treatment, if necessary.
  • Examples of natural graphite include earthy graphite, scaly graphite, and scaly graphite.
  • scaly graphite and scaly graphite are preferable, and scaly graphite is more preferable because they have a high degree of graphitization and contain few impurities.
  • artificial graphite examples include coal tar pitch, coal-based heavy oil, atmospheric residual oil, petroleum-based heavy oil, aromatic hydrocarbons, nitrogen-containing cyclic compounds, sulfur-containing cyclic compounds, polyphenylene, polyvinyl chloride, polyvinyl Examples include those obtained by heating organic substances such as alcohol, polyacrylonitrile, polyvinyl butyral, natural polymers, polyphenylene sulfide, polyphenylene oxide, furfuryl alcohol resin, phenol-formaldehyde resin, and imide resin to 2500° C. or higher to graphitize them.
  • organic substances such as alcohol, polyacrylonitrile, polyvinyl butyral, natural polymers, polyphenylene sulfide, polyphenylene oxide, furfuryl alcohol resin, phenol-formaldehyde resin, and imide resin to 2500° C. or higher to graphitize them.
  • the volume-based average particle diameter (d50) of graphite (A) is preferably 1 ⁇ m or more, more preferably 3 ⁇ m or more, and even more preferably 5 ⁇ m or more, since the specific surface area does not become too large and the activity against the electrolyte can be suppressed.
  • the volume-based average particle diameter (d50) of graphite (A) is preferably 120 ⁇ m or less, more preferably 100 ⁇ m or less, and even more preferably 90 ⁇ m or less, since this can suppress the generation of streaks and unevenness during electrode plate production.
  • the volume-based average particle diameter (d50) is the value of the volume-based median diameter measured with a laser diffraction/scattering particle size distribution analyzer. Specifically, 0.01 g of a sample was suspended in 10 mL of a 0.2% by mass aqueous solution of polyoxyethylene sorbitan monolaurate, which is a surfactant, and introduced into a laser diffraction/scattering particle size distribution analyzer. After irradiating the specimen with ultrasonic waves with an output of 60 W for 1 minute, the volume-based median diameter in the measuring device is measured.
  • the d90 of graphite (A) is preferably 1.5 ⁇ m or more, more preferably 4 ⁇ m or more, and even more preferably 6 ⁇ m or more, since it can efficiently encapsulate particles (B).
  • the d90 of graphite (A) is preferably 150 ⁇ m or less, more preferably 120 ⁇ m or less, and even more preferably 100 ⁇ m or less, since it can suppress the generation of coarse particles when encapsulating particles (B).
  • d90 is the value of the particle size corresponding to cumulative 90% from the small particle side in the particle size distribution obtained by measuring the volume-based average particle size.
  • the long axis of graphite (A) is preferably 5 ⁇ m or more, more preferably 10 ⁇ m or more, and even more preferably 15 ⁇ m or more, since it has a high capacity.
  • the long axis of graphite (A) is preferably 100 ⁇ m or less, more preferably 90 ⁇ m or less, and even more preferably 80 ⁇ m or less, since it has excellent acceptability for lithium ions.
  • the major axis is the longest diameter of a particle when observed three-dimensionally using a scanning electron microscope, and is the average value of the major axis of any 20 particles.
  • the short axis of graphite (A) is preferably 0.9 ⁇ m or more, more preferably 1.0 ⁇ m or more, and even more preferably 1.2 ⁇ m or more, since it has a high capacity.
  • the short axis of graphite (A) is preferably 3 ⁇ m or less, more preferably 2 ⁇ m or less, and even more preferably 1.5 ⁇ m or less, since it has excellent acceptability for lithium ions.
  • the shortest diameter is the shortest diameter of a particle when observed three-dimensionally using a scanning electron microscope, and is the average value of the shortest diameters of any 20 particles. .
  • the aspect ratio of graphite (A) is preferably 2.1 or more, more preferably 2.3 or more, and even more preferably 2.5 or more, since it has a high capacity.
  • the aspect ratio of graphite (A) is preferably 10 or less, more preferably 9 or less, and even more preferably 8 or less, since it has excellent acceptability for lithium ions.
  • the aspect ratio is defined by the longest diameter X of a particle when three-dimensionally observed using a scanning electron microscope, and the shortest diameter Y among the diameters orthogonal to the longest diameter, X/Y. This is the average value of the aspect ratios of any 20 particles.
  • the specific surface area (SA) of graphite (A) is preferably 1 m 2 /g or more, more preferably 2 m 2 /g or more, and 3 m 2 /g because the battery output is improved by increasing the lithium ion storage capacity of the particles. The above is more preferable.
  • the specific surface area (SA) of graphite (A) is preferably 40 m 2 /g or less, more preferably 35 m 2 /g or less, and 30 m 2 /g or less, since it can suppress a decrease in battery capacity due to an increase in the irreversible capacity of the particles. is even more preferable.
  • the specific surface area is a value measured by the BET method. Specifically, using a specific surface area measurement device, the sample is pretreated by heating it to 150°C under nitrogen flow, then cooled to liquid nitrogen temperature, and the value of the relative pressure of nitrogen to atmospheric pressure is measured. Using a nitrogen-helium mixed gas that has been precisely adjusted so that the value is 0.3, the measurement is performed by the nitrogen adsorption BET one-point method using the gas flow method.
  • the tap density of graphite (A) can suppress process defects such as streaking during electrode plate production, and improves filling properties, resulting in good rollability and easy formation of a high-density negative electrode sheet, which makes it easier to form a high-density negative electrode sheet when made into an electrode body.
  • the degree of curvature of the movement path of lithium ions is reduced and the shape of the voids between particles is adjusted, so the movement of the electrolyte becomes smooth and the rapid charging and discharging characteristics are improved . .13 g/cm 3 or more is more preferable, and 0.15 g/cm 3 or more is even more preferable.
  • the tap density of graphite (A) is 1.0 g because the particles do not become too hard due to the appropriate space on the surface and inside of the particles and have excellent electrode pressability, as well as excellent rapid charge/discharge characteristics and low-temperature input/output characteristics.
  • /cm 3 or less is preferable, 0.8 g/cm 3 or less is more preferable, and 0.6 g/cm 3 or less is still more preferable.
  • the tap density is determined by dropping the sample into a cylindrical tap cell with a diameter of 1.5 cm and a volumetric capacity of 20 cm 3 through a sieve with an opening of 300 ⁇ m, and filling the cell to the full. After that, tapping with a stroke length of 10 mm is performed 1000 times, and the density value is calculated from the volume at that time and the mass of the sample.
  • the Raman R value of graphite (A) is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more, since the larger the particle reaction surface is, the more efficiently it can react with Li.
  • the Raman R value of graphite (A) is preferably 0.7 or less, more preferably 0.6 or less, and even more preferably 0.5 or less, since the higher the graphite property, the higher the conductivity, which is suitable for batteries. preferable.
  • the Raman R value is defined as the intensity ratio ( The value is calculated as (IB/IA).
  • “near 1580 cm -1 " refers to the range of 1580 to 1620 cm -1
  • “near 1360 cm -1 " refers to the range of 1350 to 1370 cm -1 .
  • Raman spectra are measured with a Raman spectrometer. Specifically, the sample is filled by letting it fall naturally into the measurement cell, and the measurement is performed while irradiating the measurement cell with argon ion laser light and rotating the measurement cell in a plane perpendicular to the laser light. .
  • the measurement conditions are as follows.
  • Argon ion laser light wavelength 514.5nm
  • Laser power on sample 25mW Resolution: 4cm -1
  • Measurement range 1100cm -1 ⁇ 1730cm -1
  • Peak intensity measurement, peak half-width measurement background processing, smoothing processing (5 points of convolution using simple average)
  • the d002 value of graphite (A) is preferably 3.37 ⁇ or less, more preferably 3.36 ⁇ or less, because graphite is highly crystalline and has sufficient charge/discharge capacity.
  • the Lc of graphite (A) is preferably 900 ⁇ or more, more preferably 950 ⁇ or more, since graphite is highly crystalline and has sufficient charge/discharge capacity.
  • the d002 value is the value of the interplanar spacing of the lattice planes (002 planes) measured by the X-ray diffraction method according to the Jakushin method.
  • Lc is the value of the crystallite size measured by the X-ray diffraction method according to the Jakushin method.
  • the measurement conditions for X-ray diffraction are as follows. X-ray: CuK ⁇ ray Measurement range: 20° ⁇ 2 ⁇ 30° Step angle: 0.013° Sample preparation: Fill the sample plate recess with a depth of 0.2 mm with powder sample to create a flat sample surface.
  • Particle (B) Particles (B) contain at least one selected from the group consisting of tantalum compounds and cerium compounds. By containing at least one kind selected from the group consisting of tantalum compounds and cerium compounds having a large ionic radius, the particles (B) secure a diffusion path for lithium ions and improve stability against the electrolyte. The cycle characteristics of the battery can be improved.
  • tantalum compounds include tantalum oxides such as tantalum pentoxide and tantalum dioxide. These tantalum compounds may be used alone or in combination of two or more. Among these tantalum compounds, tantalum oxide is preferred, and tantalum pentoxide is preferred because of its excellent stability.
  • the crystalline state of the tantalum compound may be single crystal, polycrystal, or amorphous.
  • the tantalum compound is preferably polycrystalline or amorphous because it is easy to reduce the particle size and has excellent rate characteristics.
  • cerium compound examples include cerium oxides such as cerium (IV) oxide and cerium (III) oxide. These cerium compounds may be used alone or in combination of two or more. Among these cerium compounds, cerium oxide is preferred, and cerium (IV) oxide is more preferred because of its excellent stability.
  • the crystalline state of the cerium compound may be single crystal, polycrystal, or amorphous.
  • the cerium compound is preferably polycrystalline or amorphous because it is easy to reduce the particle size and has excellent rate characteristics.
  • the particles (B) may contain one or more tantalum compounds and one or more cerium compounds.
  • Particles (B) may contain metal elements other than tantalum and/or cerium, as long as the amount does not inhibit the functions of tantalum and/or cerium.
  • metal elements include aluminum, calcium, magnesium, niobium, europium, and hafnium.
  • the content of other metal elements is preferably 5 mol% or less with respect to 100 mol% of tantalum and/or cerium.
  • the particles (B) contain silicon element because they have a high capacity.
  • the particles (B) preferably have a tantalum compound and/or a cerium compound on the surface of the particles (B1) containing silicon element, since the stability against the electrolyte is improved.
  • the particles (B1) containing silicon element may be those containing silicon element (Si), and the Si may be simple Si or a Si compound.
  • the crystal state of the particles (B1) may be crystalline, polycrystalline, or amorphous. is preferred.
  • Si compound examples include Si oxide, Si nitride, and Si carbide.
  • SiOx is obtained using silicon dioxide (SiO 2 ) and metal Si as raw materials.
  • x is preferably larger than 0, more preferably 0.1 or more, even more preferably 0.5 or more, and particularly preferably 0.8 or more, since it can extend the life of the secondary battery.
  • x is preferably 2 or less, more preferably 1.8 or less, even more preferably 1.5 or less, and particularly preferably 1.2 or less, since it results in a high capacity.
  • the value of x in SiOx is determined by measuring the amount of oxygen in SiOx by impulse furnace heating extraction-IR detection method under an inert gas atmosphere, measuring the amount of silicon in SiOx by ICP emission spectrometry, The amount divided by the amount of silicon.
  • SiOx has a larger theoretical capacity than graphite (A), and amorphous Si or nano-sized Si crystals allow alkali ions such as lithium ions to enter and exit easily, making it possible to increase the capacity.
  • the oxygen content of the particles (B1) is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and 0.01% by mass or more, more preferably 0.03% by mass or more, based on 100% by mass of the particles (B1), since this can extend the life of the secondary battery. More preferably, the amount is 0.05% by mass or more.
  • the oxygen content of the particles (B1) is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, since it has a high capacity.
  • the oxygen content is a value measured by an impulse furnace heating extraction-IR detection method under an inert gas atmosphere.
  • oxygen may be present near the surface, oxygen may be present inside the particles, or oxygen may be present uniformly within the particles. Since the life of the secondary battery can be extended, it is preferable that oxygen in the particles (B1) exist near the surface.
  • the crystallite size is preferably 0.05 nm or more, more preferably 0.5 nm or more, and even more preferably 1 nm or more, since the battery output is improved.
  • the crystallite size of the particles (B1) is preferably 100 nm or less, more preferably 70 nm or less, and even more preferably 50 nm or less, since the life of the secondary battery can be extended.
  • particles (B1) commercially available ones may be used as they are, or mechanical energy may be applied to adjust the particle size before use.
  • Particles (B1) may be produced by any known method, but because of their excellent uniformity, SiOx gas generated by heating a mixture of silicon dioxide powder and metal silicon powder is precipitated by cooling.
  • the method is one in which mechanical energy is then applied. Mechanical energy may be applied using a known method.
  • Particles (B) having a tantalum compound and/or cerium compound on the surface of the particles (B1) containing silicon element may be obtained by growing a tantalum compound and/or cerium compound on the surface of the particle (B1) by a chemical reaction. Often, a tantalum compound and/or a cerium compound may be attached to the surface of the particles (B1) by applying physical energy. Since the surface of the particles (B1) containing the silicon element has excellent adhesion between the tantalum compound and/or the cerium compound, a solution containing a compound that is a raw material for the tantalum compound and/or the cerium compound is prepared, and the particles (B1) containing the silicon element are prepared.
  • B1) is impregnated in this solution, a tantalum compound and/or a cerium compound is attached to the surface of the particles (B1) containing silicon element, and the surface of the particles (B1) is coated with the tantalum compound and/or the cerium compound. is preferred.
  • one embodiment of the method for producing particles of the present invention is a method including the step of coating at least a portion of the surface of the particles (B1) containing silicon element with a tantalum compound and/or a cerium compound. . After attaching the tantalum compound and/or the cerium compound to the surface of the particles (B1) containing the silicon element, heat treatment may be performed.
  • the cerium compound may be grown on the surface of the particle (B1) by a chemical reaction, or by a physical reaction.
  • the cerium compound may be attached to the surface of the particles (B1) by applying energy, but since the cerium compound has excellent adhesion to the surface of the particles (B1) containing the silicon element, A preferred method is to prepare a solution containing silicon, impregnate particles (B1) containing silicon element in this solution, and adhere the cerium compound to the surface of the particles (B1) containing silicon element. After the cerium compound is attached to the surface of the particles (B1) containing silicon element, heat treatment may be performed.
  • the content of the tantalum element and/or the cerium element in the particles (B) is preferably 1 atomic part or more, more preferably 3 atomic parts or more, based on 100 atomic parts of silicon element, since it can suppress the reaction with the electrolytic solution. , more preferably 5 atomic parts or more.
  • the content of the tantalum element and/or the cerium element in the particles (B) is 25 atoms because the content of the particles (B1) containing the silicon element is relatively large, so that the particles of the present invention have a high capacity.
  • the amount is preferably at most 20 atomic parts, more preferably at most 20 atomic parts, even more preferably at most 15 atomic parts.
  • the volume-based average particle diameter (d50) of the particles (B) is preferably 0.2 ⁇ m or more, more preferably 0.3 ⁇ m or more, and even more preferably 0.4 ⁇ m or more, since the density of the active material layer can be increased.
  • the volume-based average particle diameter (d50) of the particles (B) is preferably 10 ⁇ m or less, more preferably 3 ⁇ m or less, and even more preferably 0.8 ⁇ m or less, since it has excellent lithium ion acceptability.
  • the maximum particle diameter dmax of the particles (B) is preferably 0.3 ⁇ m or more, more preferably 0.5 ⁇ m or more, and even more preferably 1 ⁇ m or more, since it provides a high capacity.
  • the maximum particle diameter dmax of the particles (B) is preferably 20 ⁇ m or less, more preferably 5 ⁇ m or less, and even more preferably 2 ⁇ m or less, since particles (B) that are insufficiently composited with graphite (A) can be reduced.
  • the volume-based average particle diameter (d50) of the particles (B) is the volume-based average particle size of the particles (B) obtained by heating the particles of the present invention in the presence of oxygen to burn and remove graphite (A).
  • the diameter (d50) may be measured using the measurement method described above.
  • the maximum particle size dmax is defined as the value of the largest measured particle size of particles in the particle size distribution obtained during the measurement of the volume-based average particle size (d50).
  • the specific surface area (SA) of the particles (B) is preferably 0.5 m 2 /g or more, more preferably 0.8 m 2 /g or more, and still more preferably 1 m 2 /g or more, since it has excellent acceptability for lithium ions. preferable.
  • the specific surface area (SA) of the particles (B) is preferably 120 m 2 /g or less, more preferably 110 m 2 /g or less, and even more preferably 100 m 2 /g or less, since the battery output is improved.
  • the content of cerium element in the particles (B) containing a cerium compound in the second particles of the present invention is 0.1 parts by mass or more based on 100 parts by mass of silicon element, since the reaction with the electrolyte can be suppressed. It is preferably 0.4 parts by mass or more, more preferably 1 part by mass or more.
  • the content of the cerium element in the particles (B) is 10 parts by mass or less, since the content of the particles (B1) containing the silicon element is relatively large, so that the second particles of the present invention have a high capacity. is preferable, 8 parts by mass or less is more preferable, and even more preferably 5 parts by weight or less.
  • the volume-based average particle diameter (d50) of the particles (B) in the second particles of the present invention is preferably 0.2 ⁇ m or more, more preferably 0.3 ⁇ m or more, and 0.2 ⁇ m or more, more preferably 0.3 ⁇ m or more, since the density of the active material layer can be increased. More preferably, the thickness is 4 ⁇ m or more.
  • the volume-based average particle diameter (d50) of the particles (B) is preferably 10 ⁇ m or less, more preferably 3 ⁇ m or less, and even more preferably 0.8 ⁇ m or less, since it has excellent lithium ion acceptability.
  • the maximum particle diameter dmax of the particles (B) in the second particles of the present invention is preferably 0.3 ⁇ m or more, more preferably 0.5 ⁇ m or more, and even more preferably 1 ⁇ m or more, since it has a high capacity.
  • the maximum particle diameter dmax of the particles (B) is preferably 20 ⁇ m or less, more preferably 5 ⁇ m or less, and even more preferably 2 ⁇ m or less, since particles (B) that are insufficiently composited with graphite (A) can be reduced.
  • the specific surface area (SA) of the particles (B) in the second particles of the present invention is preferably 0.5 m 2 /g or more, more preferably 0.8 m 2 /g or more, since it has excellent acceptability for lithium ions. , more preferably 1 m 2 /g or more.
  • the specific surface area (SA) of the particles (B) is preferably 120 m 2 /g or less, more preferably 110 m 2 /g or less, and even more preferably 100 m 2 /g or less, since the battery output is improved.
  • the particles of the present invention have a carbonaceous substance on the surface because the specific surface area can be reduced when graphite (A) and particles (B) described below are composited.
  • the carbonaceous substances contained in the particles of the present invention will be described later.
  • the content of graphite (A) in the particles of the present invention is determined to be 100% by mass in total of graphite (A) and particles (B), since it is easy to composite graphite (A) and particles (B), which will be described later. %, preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more.
  • the content of graphite (A) in the particles of the present invention is preferably 95% by mass or less, preferably 92% by mass or less, and more preferably 90% by mass or less, since it has a high capacity.
  • the content of particles (B) in the particles of the present invention is preferably 5% by mass or more, and 8% by mass or more out of the total 100% by mass of graphite (A) and particles (B), since it has a high capacity.
  • the content is more preferably 10% by mass or more.
  • the content of particles (B) in the particles of the present invention is preferably 40% by mass or less, and preferably 30% by mass or less, since it is easy to composite graphite (A) and particles (B), which will be described later. , more preferably 20% by mass or less.
  • the content of the carbonaceous substance decreases the specific surface area of the particles of the present invention and has excellent initial charge/discharge efficiency.
  • the amount is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more.
  • the content of the carbonaceous material is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, in order to obtain a high capacity.
  • the carbonaceous material may contain alloyable metal particles and carbon fine particles in addition to the amorphous carbonaceous material and the graphitized material.
  • shape of the carbon fine particles include granules, spheres, chains, needles, fibers, plates, and scales.
  • Specific examples of carbon fine particles include fine coal powder, gas phase carbon powder, carbon black, Ketjenblack, carbon nanofibers, and the like. These carbon fine particles may be used alone or in combination of two or more. Among these carbon fine particles, carbon black is preferred because it has excellent low-temperature input/output characteristics.
  • the volume-based average particle diameter (d50) of the particles of the present invention is preferably 1 ⁇ m or more, more preferably 4 ⁇ m or more, and even more preferably 6 ⁇ m or more, since the specific surface area does not become too large and the activity against the electrolyte can be suppressed.
  • the volume-based average particle diameter (d50) of the particles of the present invention is preferably 50 ⁇ m or less, more preferably 40 ⁇ m or less, and even more preferably 30 ⁇ m or less, since this can suppress the generation of streaks and unevenness during electrode plate production.
  • the specific surface area (SA) of the particles of the present invention is preferably 0.1 m 2 /g or more, more preferably 0.7 m 2 /g or more, since battery output is improved by increasing the lithium ion storage capacity of the particles. More preferably, it is 1 m 2 /g or more.
  • the specific surface area (SA) of the particles of the present invention is preferably 40 m 2 /g or less, more preferably 35 m 2 /g or less, and even more preferably 30 m 2 /g or less, since the particles can suppress activity with respect to the electrolyte.
  • the tap density of the particles of the present invention is preferably 0.5 g/cm 3 or more, and 0.6 g/cm 3 or more, since the shape of the voids between particles is arranged, smoothing the movement of the electrolyte and improving rapid charge/discharge characteristics. cm 3 or more is more preferable, and 0.8 g/cm 3 or more is even more preferable.
  • the tapped density of the particles of the present invention is preferably 2.2 g/cm 3 or less, more preferably 2.0 g/cm 3 or less, and 1.9 g/cm 3 or less, since the tap density of the particles of the present invention is excellent in the volumetric energy density of the secondary battery. More preferred.
  • the d002 value of the particles of the present invention is preferably 3.37 ⁇ or less, more preferably 3.36 ⁇ or less, because graphite is highly crystalline and has sufficient charge/discharge capacity.
  • the Lc of the particles of the present invention is preferably 900 ⁇ or more, more preferably 950 ⁇ or more, since graphite is highly crystalline and has sufficient charge and discharge capacity.
  • the Raman R value of the particles of the present invention is preferably 0.05 or more, more preferably 0.1 or more because it has excellent conductivity, and preferably 0.4 or less and 0.35 or less because it has high capacity. is more preferable.
  • the method for producing particles of the present invention is preferably a method of compounding graphite (A) and particles (B) because it improves battery output, and graphite (A) and particles (B) are preferably composited because the life of the secondary battery can be extended. It is more preferable to subject A) and particles (B) to a spheroidization treatment to form a composite. By subjecting graphite (A) and particles (B) to a spheroidizing process to form a composite, particles in which particles (B) are encapsulated in graphite (A) can be obtained.
  • one embodiment of the present invention is a method for producing particles including a step of encapsulating particles (B) containing at least one selected from the group consisting of tantalum compounds and cerium compounds in graphite (A). Moreover, this method preferably further includes a step of coating the surface of the particles (B1) containing silicon element with at least one member selected from the group consisting of tantalum compounds and cerium compounds.
  • Step (1) A step of mixing graphite (A) and particles (B).
  • Step (2) A step of applying mechanical energy to the mixture obtained in step (1) and spheroidizing it.
  • Step (1) is a step of mixing graphite (A) and particles (B).
  • a known mixing method can be used.
  • Step (2) is a step of applying mechanical energy to the mixture obtained in step (1) to form a spheroid.
  • the device for applying mechanical energy is preferably a hybridization system.
  • the hybridization system has a rotor with a large number of blades that imparts mechanical energy of impact, compression, friction and shear, and the rotation of the rotor generates a large air current, which causes a large centrifugal force on the graphite (A) in the mixture. Due to the force applied, the graphite (A) collides with each other, and the graphite (A) collides with the wall or blade, so that the composite of graphite (A) and particles (B) progresses efficiently.
  • the circumferential speed of the rotor is preferably 30 m/sec or more, more preferably 40 m/sec or more, and even more preferably 50 m/sec or more, since the efficiency of compounding is excellent.
  • the circumferential speed of the rotor is preferably 120 m/sec or less, more preferably 110 m/sec or less, and even more preferably 100 m/sec or less, since heat generation due to collision energy can be suppressed.
  • the rotation time of the rotor is preferably 0.5 minutes or more, more preferably 1 minute or more, and even more preferably 2 minutes or more, since the uniformity of compounding is excellent.
  • the rotation time of the rotor is preferably 60 minutes or less, more preferably 30 minutes or less, and even more preferably 10 minutes or less, since the capacity is high.
  • a granulating agent may be added to the mixture, if necessary.
  • a known granulating agent can be used as the granulating agent.
  • the method for producing particles of the present invention preferably further includes the following step (3) because the specific surface area of the particles can be easily controlled.
  • step (3) particles of the present invention having a carbonaceous substance on the surface are obtained.
  • Step (3) A step of coating the surface of particles (hereinafter sometimes referred to as "particles (C)") containing graphite (A) and particles (B) with a carbonaceous material.
  • Examples of the carbonaceous substance include amorphous carbonaceous substances and graphitized substances, but amorphous carbonaceous substances are preferable because they have excellent acceptability for lithium ions.
  • the amorphous carbonaceous material refers to carbon having a d002 value of 0.340 nm or more.
  • Graphite material refers to graphite having a d002 value of less than 0.340 nm.
  • the method of coating the surface of the particles (C) with an amorphous carbonaceous substance or a graphite substance has excellent coating efficiency, and therefore, the particles are mixed with an amorphous carbonaceous substance precursor or a graphite substance precursor, and a non-oxidizing Preferred is a method in which the amorphous carbonaceous material precursor is amorphous carbonized or the graphitic material precursor is graphitized by heating in an atmosphere.
  • the particles (C) and the amorphous carbonaceous material precursor or the graphite material precursor are mixed using a mixer or a kneader.
  • examples include a method in which the particles (C) are added to a solution in which an amorphous carbonaceous material precursor or a graphite material precursor is dissolved and the solvent is removed.
  • a method of mixing particles (C) and an amorphous carbonaceous material precursor or a graphite material precursor using a mixer or a kneader is preferable because it can efficiently reduce micropores of 1 nm to 4 nm. .
  • the atmosphere during heating after mixing is not particularly limited as long as it is a non-oxidizing atmosphere, but nitrogen, argon, and carbon dioxide are preferable, and nitrogen is more preferable because the initial efficiency of the secondary battery is excellent.
  • the oxygen concentration of the non-oxidizing atmosphere is preferably 1% by volume or less, more preferably 0.1% by volume or less, since the initial efficiency of the secondary battery is excellent.
  • the heating temperature is different for amorphous carbonization of the amorphous carbonaceous material precursor and graphitization of the graphitic material precursor.
  • the heating temperature for amorphous carbonizing the amorphous carbonaceous material precursor is not particularly limited as long as it does not reach a crystal structure equivalent to that of graphite, but is preferably 500°C or higher, and 600°C or higher. is more preferable, 700°C or higher is still more preferable, 2000°C or lower is preferable, 1800°C or lower is more preferable, and even more preferably 1600°C or lower.
  • the heating temperature when graphitizing the graphite substance precursor is not particularly limited as long as it reaches a crystal structure equivalent to that of graphite, but is preferably 2100°C or higher, more preferably 2500°C or higher, and 2700°C or higher. is more preferable, 3300°C or less is preferable, 3200°C or less is more preferable, and even more preferably 3100°C or less.
  • the heating time is preferably 0.1 hour or more, more preferably 1 hour or more, since the degree of graphitization is suitable for a secondary battery.
  • the heating time is preferably 1000 hours or less, more preferably 100 hours or less, since byproducts due to the reaction between graphite (A) and particles (B) can be suppressed.
  • amorphous carbonaceous material precursor and graphite material precursor examples include tar, pitch, aromatic hydrocarbons such as naphthalene and anthracene, and thermoplastic resins such as phenol resin and polyvinyl alcohol resin. These precursors may be used alone or in combination of two or more. Among these precursors, tar, pitch, and aromatic hydrocarbons are preferable because they allow carbon structures to develop easily and can be coated with a small amount, and those with a residual carbon content of 50% or more are more preferable, and those with a residual carbon content of 60% are preferable. The above are more preferred.
  • the ash content in the amorphous carbonaceous material precursor or graphite material precursor can extend the life of the secondary battery, it should be 0.00001% by mass or more in 100% by mass of the amorphous carbonaceous material precursor or graphite material precursor.
  • the content is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less.
  • the metal impurity content in the amorphous carbonaceous material precursor or graphite material precursor is 0.1% by mass of the amorphous carbonaceous material precursor or graphite material precursor, since this can extend the life of the secondary battery. It is preferably at least 1000 ppm by mass, more preferably at most 500 ppm by mass, and even more preferably at most 100 ppm by mass.
  • the metal impurity content is the value obtained by dividing the total content of Fe, Al, Si, and Ca in the amorphous carbonaceous material precursor or graphite material precursor by the residual carbon percentage.
  • Qi quinoline insoluble content
  • the amorphous carbonaceous material precursor and graphite material precursor can extend the life of the secondary battery, so it is It is preferably at most 3% by mass, more preferably at most 3% by mass.
  • the particles of the present invention may be pulverized, crushed, and classified as necessary in order to adjust the volume-based average particle size to a desired range.
  • pulverization, crushing, and classification known methods can be used.
  • the method for producing a negative electrode of the present invention includes a step of applying particles of the present invention onto a current collector.
  • the negative electrode manufactured by the negative electrode manufacturing method of the present invention (hereinafter sometimes referred to as "the negative electrode of the present invention") includes a current collector and an active material layer formed on the current collector, The active material layer contains particles of the present invention.
  • the particles of the present invention have the effect of functioning as a negative electrode active material.
  • the method for producing the negative electrode of the present invention is not particularly limited as long as an active material layer can be formed on the current collector, but since it has excellent uniformity, a slurry containing the particles of the present invention and a binder is coated on the current collector. A method of drying is preferred.
  • the slurry may further contain a thickener.
  • the density of the active material layer is preferably 1.5 g/cm 3 or more, more preferably 1.6 g/cm 3 or more because it can suppress a decrease in battery capacity per unit volume, and it can suppress a decrease in rate characteristics. , 2.0 g/cm 3 or less is preferable, and 1.9 g/cm 3 or less is more preferable.
  • the method for manufacturing a secondary battery of the present invention is a method for manufacturing a secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode is the negative electrode of the present invention obtained by the manufacturing method of the present invention.
  • the positive electrode and the negative electrode of the present invention are preferably capable of intercalating and deintercalating lithium ions.
  • a known positive electrode can be used as the positive electrode.
  • Electrodes A known electrolyte can be used as the electrolyte.
  • a separator In the secondary battery, it is preferable that a separator is interposed between the positive electrode and the negative electrode.
  • a known separator can be used as the separator.
  • the particles of the present invention have an excellent effect of improving cycle characteristics of secondary batteries, they can be suitably used as an active material for a negative electrode of a secondary battery, and are more suitably used as an active material for a negative electrode of a non-aqueous secondary battery. It can be particularly suitably used as an active material for a negative electrode of a lithium ion secondary battery.
  • volume-based average particle diameter 0.01 g of the sample was suspended in 10 mL of a 0.2% by mass aqueous solution of polyoxyethylene sorbitan monolaurate (trade name "Tween 20"), which is a surfactant, and a laser diffraction/scattering particle size distribution analyzer (model ⁇ LA-920'' (manufactured by Horiba, Ltd.) and irradiated with 28kHz ultrasonic waves at an output of 60W for 1 minute, the volume-based median diameter of the measurement device was measured, and the volume-based median diameter was measured. It was defined as the volume-based average particle diameter.
  • Argon ion laser light wavelength 514.5nm
  • Laser power on sample 25mW Resolution: 4cm -1
  • Measurement range 1100cm -1 ⁇ 1730cm -1
  • Peak intensity measurement, peak half-width measurement background processing, smoothing processing (5 points of convolution using simple average)
  • the active material layer was roll pressed using a 250 mm ⁇ roll press equipped with a load cell so that the density of the active material layer was 1.6 to 1.7 g/cm 3 , punched out into a circular shape with a diameter of 12.5 mm, and vacuumed at 90°C for 8 hours. It was dried to obtain a negative electrode for evaluation.
  • the obtained negative electrode and a lithium foil as a counter electrode were stacked with a separator impregnated with an electrolytic solution interposed therebetween to obtain a battery for a charge/discharge test.
  • the battery for charge/discharge test was charged at a current density of 0.08 mA/cm 2 until the voltage reached 5 mV, and then at a constant voltage of 5 mV until the current value reached 0.03 mA/cm 2 .
  • discharging was performed at a current density of 0.2 mA/cm 2 until the voltage of the battery reached 1.5 V (initial first cycle).
  • ⁇ Charging'' refers to passing a current in a direction in which lithium is doped into the negative electrode for evaluation
  • ⁇ discharging'' refers to passing a current in a direction in which lithium is dedoped from the negative electrode for evaluation.
  • the initial discharge capacity (mAh/g) is calculated by subtracting the mass of the copper foil punched to the same area as the negative electrode from the mass of the negative electrode, and then dividing the discharge capacity at the initial 5th cycle by the mass of the negative electrode active material.
  • the battery was charged at a current density of 1 mA/cm 2 until the voltage of the battery after the initial charging and discharging reached 5 mV, and further charged at a constant voltage of 5 mV until the current value reached 0.1 mA/cm 2 .
  • the battery was discharged at a current density of 1 mA/cm 2 until the voltage of the battery reached 1.5 V (first cycle). Thereafter, charging and discharging were repeated 9 times under the same conditions as the first cycle (2nd cycle to 10th cycle).
  • the capacity retention rate (%) at the 10th cycle was calculated using the following formula (1).
  • 10th cycle capacity retention rate (%) ⁇ 10th cycle discharge capacity (mAh)/1st cycle charge capacity (mAh) ⁇ x 100 (1)
  • the charge/discharge efficiency (%) at the 10th cycle was calculated using the following formula (2).
  • 10th cycle charge/discharge efficiency (%) ⁇ 10th cycle discharge capacity (mAh)/10th cycle charge capacity (mAh) ⁇ 100 (2)
  • the obtained sol solution of tantalum oxide was added dropwise to a suspension of 100 parts by mass of particles (B1-1) containing silicon element dispersed in 124.4 parts by mass of ethanol, and after stirring at 25 ° C. for 60 minutes, The solvent was distilled off under reduced pressure at 60°C to obtain a powder.
  • the obtained powder was heated at 120°C for 6 hours and further heated at 500°C for 1 hour in an air atmosphere. Thereafter, the obtained powder was crushed with an agate to obtain particles (B-1) containing tantalum oxide on the surface of particles (B1-1) containing silicon element.
  • the obtained particles (B-1) contained 13 atomic parts of tantalum element per 100 atomic parts of silicon element, and it was confirmed that the tantalum oxide contained tantalum pentoxide.
  • Scaly graphite (A-1) volume-based average particle diameter: 11.1 ⁇ m, d90: 21.1 ⁇ m, specific surface area: 9.9 m 2 /g, tap density: 0.44 g/cm 3 , Raman R value: 0 .28) 88.5% by mass and 11.5% by mass of particles (B-1) were mixed, a granulating agent was added thereto, and the mixture was stirred and mixed using a stirring granulator. The obtained mixture was put into a hybridization system, and subjected to mechanical granulation and spheroidization for 5 minutes at a rotor circumferential speed of 85 m/sec.
  • the granulating agent was removed by heat treatment to obtain spherical composite particles.
  • the obtained spherical composite particles and pitch (ash content: 0.02 mass %, metal impurity content: 20 mass ppm, Qi: 1 mass %) were mixed and heat treated at 1000 ° C. in an inert gas.
  • a fired product was obtained.
  • the obtained fired product was crushed and classified to obtain particles containing graphite (A-1) and particles (B-1). Table 1 shows the evaluation results of the obtained particles.
  • Example 2 Particles containing graphite (A-1) and particles (B-2) were obtained by performing the same operation as in Example 1, except that particles (B-1) were changed to particles (B-2). Ta. Table 1 shows the evaluation results of the obtained particles.
  • Example 3 3.6 parts by mass of cerium (IV) ethoxide was added to a solution of 1.6 parts by mass of acetic acid and 65.4 parts by mass of ethanol, and after stirring at 25°C for 30 minutes, 8.6 parts by mass of acetic acid and 51 parts by mass of ethanol were added. A solution containing 4.4 parts by mass of diethanolamine and 40 parts by mass of ethanol was added dropwise, and the mixture was stirred at 25° C. for 30 minutes to obtain a sol solution of a cerium compound.
  • the obtained cerium compound sol solution was added dropwise to a suspension of 100 parts by mass of particles (B1-1) containing silicon element dispersed in 124.4 parts by mass of ethanol, and after stirring at 25°C for 60 minutes, The solvent was distilled off under reduced pressure at °C to obtain a powder.
  • the obtained powder was heated at 120°C for 6 hours and further heated at 500°C for 1 hour in an air atmosphere. Thereafter, the obtained powder was crushed with an agate to obtain particles (B-3) having a cerium compound on the surface of particles (B1-1) containing silicon element.
  • the obtained particles (B-3) contained 2.2 parts by mass of cerium element per 100 parts by mass of silicon element, and it was confirmed that the cerium compound contained cerium (IV) oxide.
  • the evaluation results of the obtained particles (B-3) are shown in Table 2.
  • Example 4 Particles (B-4) were prepared in the same manner as in Example 1, except that heating at 500°C for 1 hour in an air atmosphere was changed to heating at 500°C for 1 hour in a nitrogen atmosphere. Obtained.
  • the obtained particles (B-4) contained 2.1 parts by mass of cerium element per 100 parts by mass of silicon element, and it was confirmed that the cerium compound contained cerium (IV) oxide.
  • Table 2 shows the evaluation results of the obtained particles.
  • Example 5 Particles (B-5) were obtained in the same manner as in Example 4, except that 3.6 parts by mass of cerium (IV) ethoxide was changed to 7.2 parts by mass.
  • the obtained particles (B-5) contained 4.2 parts by mass of cerium element per 100 parts by mass of silicon element, and it was confirmed that the cerium compound contained cerium (IV) oxide.
  • Table 2 shows the evaluation results of the obtained particles.
  • Example 6 Scaly graphite (A-1) (volume-based average particle diameter: 11.1 ⁇ m, d90: 21.1 ⁇ m, specific surface area: 9.9 m 2 /g, tap density: 0.44 g/cm 3 , Raman R value: 0 .28) 88.5% by mass and 11.5% by mass of particles (B-3) obtained in Example 3 were mixed, a granulating agent was added thereto, and the mixture was stirred and mixed using a stirring granulator. The obtained mixture was put into a hybridization system, and subjected to mechanical granulation and spheroidization for 5 minutes at a rotor circumferential speed of 85 m/sec.
  • the granulating agent was removed by heat treatment to obtain spherical composite particles.
  • the obtained spherical composite particles and pitch (ash content: 0.02 mass %, metal impurity content: 20 mass ppm, Qi: 1 mass %) were mixed and heat treated at 1000 ° C. in an inert gas.
  • a fired product was obtained.
  • the obtained fired product was crushed and classified to obtain particles containing graphite (A-1) and particles (B-3). Table 3 shows the evaluation results of the obtained particles.
  • the particles of the present invention can provide a secondary battery with excellent cycle characteristics as a negative electrode material for a secondary battery, they can be suitably used as an active material for a negative electrode of a secondary battery, and can be used for non-aqueous secondary batteries. It can be more suitably used as an active material for a negative electrode of a lithium ion secondary battery, and can be particularly suitably used as an active material for a negative electrode of a lithium ion secondary battery.

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Abstract

This particles comprise graphite (A) and particles (B) including at least one type selected from the group consisting of tantalum compounds and cerium compounds, wherein the particles (B) are contained in the graphite (A). The particles include the particles (B) including the cerium compound, and the surfaces of particles (B1) including a silicon element are coated with the cerium compound.

Description

粒子、粒子の製造方法、負極の製造方法及び二次電池の製造方法Particles, particle manufacturing method, negative electrode manufacturing method, and secondary battery manufacturing method
　本発明は、粒子、粒子の製造方法、負極の製造方法及び二次電池の製造方法に関する。 The present invention relates to particles, a method for producing particles, a method for producing a negative electrode, and a method for producing a secondary battery.
　近年、電子機器の小型化に伴い、高容量の二次電池に対する需要が高まってきている。特に、ニッケル・カドミウム電池やニッケル・水素電池に比べ、よりエネルギー密度が高く、充放電特性に優れた二次電池、とりわけリチウムイオン二次電池が注目されている。リチウムイオン二次電池として、リチウムイオンを吸蔵・放出できる正極及び負極、並びにＬｉＰＦ６やＬｉＢＦ４等のリチウム塩を溶解させた非水電解液からなる非水系リチウム二次電池が開発され、実用化されている。 In recent years, as electronic devices have become smaller, demand for high-capacity secondary batteries has been increasing. In particular, secondary batteries, especially lithium ion secondary batteries, are attracting attention because of their higher energy density and superior charging and discharging characteristics compared to nickel-cadmium batteries and nickel-hydrogen batteries. As a lithium ion secondary battery, a nonaqueous lithium secondary battery consisting of a positive electrode and a negative electrode that can absorb and release lithium ions, and a nonaqueous electrolyte in which lithium salts such as LiPF 6 and LiBF 4 are dissolved has been developed and put into practical use. has been done.
　従来、リチウムイオン二次電池の高性能化は広く検討されているが、近年、リチウムイオン二次電池の更なる高性能化が要求されている。例えば、特許文献１では、ケイ素粒子を内包した複合黒鉛粒子の負極材が提案されている。 In the past, improving the performance of lithium ion secondary batteries has been widely studied, but in recent years, there has been a demand for even higher performance of lithium ion secondary batteries. For example, Patent Document 1 proposes a negative electrode material of composite graphite particles containing silicon particles.
国際公開２０１５／１４７１２３号International Publication 2015/147123
　特許文献１で開示されている負極材は、ケイ素粒子に被覆等の処理が行われておらず、電解液との副反応が起こるため、二次電池のサイクル特性が十分とは言えない。
　このように、従前、様々な種類の負極材が検討されてきたが、二次電池のサイクル特性を十分に改善することができる負極材は見出されていなかった。 In the negative electrode material disclosed in Patent Document 1, the silicon particles are not coated or otherwise treated, and a side reaction with the electrolyte occurs, so that the cycle characteristics of the secondary battery cannot be said to be sufficient.
As described above, various types of negative electrode materials have been studied in the past, but no negative electrode material has been found that can sufficiently improve the cycle characteristics of secondary batteries.
　本発明の目的は、二次電池の負材料として優れたサイクル特性を得ることができる粒子を提供することにある。また、本発明の目的は、前記粒子を得るための粒子の製造方法を提供することにある。 An object of the present invention is to provide particles that can provide excellent cycle characteristics as a negative material for secondary batteries. Another object of the present invention is to provide a method for producing particles for obtaining the particles.
　本発明者らは、黒鉛に、タンタル酸化物及び／又はセリウム化合物を含む粒子（Ｂ）が内包された粒子、或いはケイ素元素を含む粒子（Ｂ１）の表面にセリウム化合物が被覆された粒子（Ｂ）を含む粒子を用いることで、二次電池のサイクル特性が改善されることを見出し、本発明に至った。 The present inventors have developed particles in which particles (B) containing tantalum oxide and/or cerium compound are encapsulated in graphite, or particles (B1) in which the surface of particles (B1) containing silicon element is coated with a cerium compound. ) was found to improve the cycle characteristics of a secondary battery, leading to the present invention.
　即ち、本発明の要旨は、以下の通りである。
［１］　黒鉛（Ａ）と、タンタル化合物及びセリウム化合物からなる群より選ばれる少なくとも１種を含む粒子（Ｂ）と、を含む粒子であって、粒子（Ｂ）が黒鉛（Ａ）に内包されたものである、粒子。
［２］　黒鉛（Ａ）のラマンＲ値が、０．１～０．７である、［１］に記載の粒子。
［３］　粒子（Ｂ）が、更に、ケイ素元素を含む、［１］又は［２］に記載の粒子。
［４］　粒子（Ｂ）が、ケイ素元素を含む粒子（Ｂ１）の表面にタンタル化合物及びセリウム化合物からなる群より選ばれる少なくとも１種が被覆されたものである、［２］に記載の粒子。
［５］　タンタル化合物が、五酸化タンタルを含む、［１］～［４］のいずれかに記載の粒子。
［６］　セリウム化合物が、酸化セリウム（ＩＶ）を含む、［１］～［５］のいずれかに記載の粒子。
［７］　粒子（Ｂ）の体積基準平均粒径が、０．２μｍ～０．８μｍである、［１］～［６］のいずれかに記載の粒子。
［８］　表面に炭素質物を有する、［１］～［７］のいずれかに記載の粒子。
［９］　黒鉛（Ａ）と粒子（Ｂ）の合計１００質量％中、黒鉛（Ａ）の含有率が６０質量％～９５質量％であり、粒子（Ｂ）の含有率が５質量％～４０質量％である、［１］～［８］のいずれかに記載の粒子。
［１０］　黒鉛（Ａ）に、タンタル化合物及びセリウム化合物からなる群より選ばれる少なくとも１種を含む粒子（Ｂ）を内包する工程を含む、粒子の製造方法。
［１１］　黒鉛（Ａ）のラマンＲ値が、０．１～０．７である、［１０］に記載の粒子の製造方法。
［１２］　更に、ケイ素元素を含む粒子（Ｂ１）の表面にタンタル化合物及びセリウム化合物からなる群より選ばれる少なくとも１種を被覆する工程を含む、［１０］又は［１１］に記載の粒子の製造方法。
［１３］　セリウム化合物を含む粒子（Ｂ）を含む粒子であって、ケイ素元素を含む粒子（Ｂ１）の表面にセリウム化合物が被覆されたものである、粒子。
［１４］　粒子（Ｂ）の体積基準平均粒径が、０．２μｍ～０．８μｍである、［１３］に記載の粒子。
［１５］　集電体上に、［１］～［９］、［１３］～［１４］のいずれかに記載の粒子を塗布する工程を含む、負極の製造方法。
［１６］　正極、負極及び電解質を含む二次電池の製造方法であって、負極が、［１５］に記載の製造方法により得られたものである、二次電池の製造方法。 That is, the gist of the present invention is as follows.
[1] Particles containing graphite (A) and particles (B) containing at least one selected from the group consisting of tantalum compounds and cerium compounds, wherein the particles (B) are encapsulated in the graphite (A). Particles.
[2] The particles according to [1], wherein the graphite (A) has a Raman R value of 0.1 to 0.7.
[3] The particle according to [1] or [2], wherein the particle (B) further contains silicon element.
[4] The particle according to [2], wherein the particle (B) is a particle (B1) containing silicon element whose surface is coated with at least one selected from the group consisting of a tantalum compound and a cerium compound.
[5] The particles according to any one of [1] to [4], wherein the tantalum compound contains tantalum pentoxide.
[6] The particle according to any one of [1] to [5], wherein the cerium compound contains cerium (IV) oxide.
[7] The particles according to any one of [1] to [6], wherein the particles (B) have a volume-based average particle diameter of 0.2 μm to 0.8 μm.
[8] The particle according to any one of [1] to [7], which has a carbonaceous substance on the surface.
[9] Out of a total of 100% by mass of graphite (A) and particles (B), the content of graphite (A) is 60% by mass to 95% by mass, and the content of particles (B) is 5% by mass to 40% by mass. The particles according to any one of [1] to [8], which are % by mass.
[10] A method for producing particles, including a step of encapsulating particles (B) containing at least one selected from the group consisting of tantalum compounds and cerium compounds in graphite (A).
[11] The method for producing particles according to [10], wherein the graphite (A) has a Raman R value of 0.1 to 0.7.
[12] The production of particles according to [10] or [11], further comprising the step of coating the surface of the particles (B1) containing silicon element with at least one selected from the group consisting of tantalum compounds and cerium compounds. Method.
[13] A particle containing a cerium compound-containing particle (B), which is a particle containing a silicon element (B1) whose surface is coated with a cerium compound.
[14] The particles according to [13], wherein the particles (B) have a volume-based average particle diameter of 0.2 μm to 0.8 μm.
[15] A method for producing a negative electrode, comprising a step of applying particles according to any one of [1] to [9] and [13] to [14] on a current collector.
[16] A method for manufacturing a secondary battery including a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode is obtained by the manufacturing method described in [15].
　本発明の粒子は、二次電池の負極の活物質として用いることで、サイクル特性に優れた二次電池を提供することができる。
　本発明の粒子の製造方法によれば、このような粒子を製造することができる。 By using the particles of the present invention as an active material for a negative electrode of a secondary battery, it is possible to provide a secondary battery with excellent cycle characteristics.
According to the method for producing particles of the present invention, such particles can be produced.
　以下に本発明について詳述する。本発明は、以下の実施の形態に限定されるものではなく、その要旨の範囲内で種々に変更して実施することができる。
　本明細書において「～」という表現を用いる場合、その前後の数値又は物性値を含む表現として用いるものとする。 The present invention will be explained in detail below. The present invention is not limited to the following embodiments, and can be implemented with various modifications within the scope of the gist.
When the expression "~" is used in this specification, it is used as an expression that includes numerical values or physical property values before and after it.
　［粒子］
　本発明の粒子は、その一実施形態において、黒鉛（Ａ）と、タンタル化合物及びセリウム化合物からなる群より選ばれる少なくとも１種を含む粒子（Ｂ）（以下、単に「粒子（Ｂ）」と称す場合がある。）とを含む粒子であって、粒子（Ｂ）が黒鉛（Ａ）に内包された粒子である。
　本発明の別の実施形態において、本発明の粒子は、セリウム化合物を含む粒子（Ｂ）を含む粒子であって、ケイ素元素を含む粒子（Ｂ１）の表面にセリウム化合物が被覆された粒子である。以下、この粒子を「本発明の第２の粒子」と称す場合がある。
　粒子（Ｂ）が黒鉛（Ａ）に内包されていることで、或いはケイ素元素を含む粒子（Ｂ１）の表面にセリウム化合物が被覆されていることで、電解液に対する安定性が向上するため、二次電池のサイクル特性を高めることができる。 [particle]
In one embodiment, the particles of the present invention are particles (B) containing graphite (A) and at least one selected from the group consisting of tantalum compounds and cerium compounds (hereinafter simply referred to as "particles (B)"). ), in which the particle (B) is encapsulated in graphite (A).
In another embodiment of the present invention, the particle of the present invention is a particle containing a particle (B) containing a cerium compound, in which the surface of the particle (B1) containing a silicon element is coated with a cerium compound. . Hereinafter, these particles may be referred to as "second particles of the present invention."
Since the particles (B) are encapsulated in the graphite (A) or the surfaces of the particles (B1) containing silicon element are coated with a cerium compound, the stability against the electrolyte is improved. The cycle characteristics of the next battery can be improved.
　本発明の第２の粒子のケイ素元素を含む粒子（Ｂ１）及びセリウム化合物については、以下の本発明の粒子におけるケイ素元素を含む粒子（Ｂ１）及びセリウム化合物の説明が同様に適用される。また、本発明の第２の粒子は、以下に説明する本発明の粒子における粒子（Ｂ）の一態様であるので、以下の説明が同様に適用される。 Regarding the particles (B1) containing the silicon element and the cerium compound of the second particles of the present invention, the following description of the particles (B1) containing the silicon element and the cerium compound in the particles of the present invention applies similarly. Further, since the second particle of the present invention is an embodiment of the particle (B) in the particles of the present invention described below, the following description applies similarly.
　本発明の粒子は、黒鉛（Ａ）と本発明の第２の粒子であるケイ素元素を含む粒子（Ｂ１）の表面にセリウム化合物が被覆された粒子とを含むものであってもよい。以下、この粒子を「本発明の第３の粒子」と称す場合がある。本発明の第３の粒子は、本発明の粒子の一態様であるので、以下の説明が同様に適用される。 The particles of the present invention may include graphite (A) and particles whose surfaces are coated with a cerium compound, particles (B1) containing silicon element, which are the second particles of the present invention. Hereinafter, this particle may be referred to as "the third particle of the present invention". Since the third particle of the present invention is one embodiment of the particle of the present invention, the following description applies similarly.
　（黒鉛（Ａ））
　黒鉛（Ａ）は、天然黒鉛、人造黒鉛のいずれを用いてもよいが、高容量であることから、天然黒鉛が好ましい。黒鉛（Ａ）は、不純物が少ないものが好ましく、必要に応じて、精製処理を施して用いることが好ましい。 (Graphite (A))
As the graphite (A), either natural graphite or artificial graphite may be used, but natural graphite is preferable because it has a high capacity. Graphite (A) preferably has few impurities, and is preferably used after being subjected to a purification treatment, if necessary.
　天然黒鉛としては、例えば、土状黒鉛、鱗状黒鉛、鱗片状黒鉛等が挙げられる。これらの天然黒鉛の中でも、黒鉛化度が高く、不純物が少ないことから、鱗状黒鉛、鱗片状黒鉛が好ましく、鱗片状黒鉛がより好ましい。 Examples of natural graphite include earthy graphite, scaly graphite, and scaly graphite. Among these natural graphites, scaly graphite and scaly graphite are preferable, and scaly graphite is more preferable because they have a high degree of graphitization and contain few impurities.
　人造黒鉛としては、例えば、コールタールピッチ、石炭系重質油、常圧残油、石油系重質油、芳香族炭化水素、窒素含有環状化合物、硫黄含有環状化合物、ポリフェニレン、ポリ塩化ビニル、ポリビニルアルコール、ポリアクリロニトリル、ポリビニルブチラール、天然高分子、ポリフェニレンサルファイド、ポリフェニレンオキシド、フルフリルアルコール樹脂、フェノール－ホルムアルデヒド樹脂、イミド樹脂等の有機物を２５００℃以上に加熱して黒鉛化したものが挙げられる。 Examples of artificial graphite include coal tar pitch, coal-based heavy oil, atmospheric residual oil, petroleum-based heavy oil, aromatic hydrocarbons, nitrogen-containing cyclic compounds, sulfur-containing cyclic compounds, polyphenylene, polyvinyl chloride, polyvinyl Examples include those obtained by heating organic substances such as alcohol, polyacrylonitrile, polyvinyl butyral, natural polymers, polyphenylene sulfide, polyphenylene oxide, furfuryl alcohol resin, phenol-formaldehyde resin, and imide resin to 2500° C. or higher to graphitize them.
　（黒鉛（Ａ）の物性）
　黒鉛（Ａ）の体積基準平均粒径（ｄ５０）は、比表面積が大きくなり過ぎず、電解液に対する活性を抑制できることから、１μｍ以上が好ましく、３μｍ以上がより好ましく、５μｍ以上が更に好ましい。黒鉛（Ａ）の体積基準平均粒径（ｄ５０）は、極板製造時に筋引きや凹凸の発生を抑制できることから、１２０μｍ以下が好ましく、１００μｍ以下がより好ましく、９０μｍ以下が更に好ましい。 (Physical properties of graphite (A))
The volume-based average particle diameter (d50) of graphite (A) is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more, since the specific surface area does not become too large and the activity against the electrolyte can be suppressed. The volume-based average particle diameter (d50) of graphite (A) is preferably 120 μm or less, more preferably 100 μm or less, and even more preferably 90 μm or less, since this can suppress the generation of streaks and unevenness during electrode plate production.
　本明細書において、体積基準平均粒径（ｄ５０）は、レーザー回折／散乱式粒度分布測定装置で測定した体積基準のメジアン径の値とする。
　具体的には、界面活性剤であるポリオキシエチレンソルビタンモノラウレートの０．２質量％水溶液１０ｍＬに、試料０．０１ｇを懸濁させ、レーザー回折／散乱式粒度分布測定装置に導入し、２８ｋＨｚの超音波を出力６０Ｗで１分間照射した後、前記測定装置における体積基準のメジアン径を測定する。 In this specification, the volume-based average particle diameter (d50) is the value of the volume-based median diameter measured with a laser diffraction/scattering particle size distribution analyzer.
Specifically, 0.01 g of a sample was suspended in 10 mL of a 0.2% by mass aqueous solution of polyoxyethylene sorbitan monolaurate, which is a surfactant, and introduced into a laser diffraction/scattering particle size distribution analyzer. After irradiating the specimen with ultrasonic waves with an output of 60 W for 1 minute, the volume-based median diameter in the measuring device is measured.
　黒鉛（Ａ）のｄ９０は、粒子（Ｂ）の内包を効率よく進めることができることから、１．５μｍ以上が好ましく、４μｍ以上がより好ましく、６μｍ以上が更に好ましい。黒鉛（Ａ）のｄ９０は、粒子（Ｂ）を内包した際に粗大粒子の生成を抑制できることから、１５０μｍ以下が好ましく、１２０μｍ以下がより好ましく、１００μｍ以下が更に好ましい。 The d90 of graphite (A) is preferably 1.5 μm or more, more preferably 4 μm or more, and even more preferably 6 μm or more, since it can efficiently encapsulate particles (B). The d90 of graphite (A) is preferably 150 μm or less, more preferably 120 μm or less, and even more preferably 100 μm or less, since it can suppress the generation of coarse particles when encapsulating particles (B).
　本発明において、ｄ９０は、体積基準平均粒径の測定で得られた粒度分布における小さい粒子側から累積９０％に相当する粒径の値とする。 In the present invention, d90 is the value of the particle size corresponding to cumulative 90% from the small particle side in the particle size distribution obtained by measuring the volume-based average particle size.
　黒鉛（Ａ）の長径は、高容量となることから、５μｍ以上が好ましく、１０μｍ以上がより好ましく、１５μｍ以上が更に好ましい。黒鉛（Ａ）の長径は、リチウムイオンの受入性に優れることから、１００μｍ以下が好ましく、９０μｍ以下がより好ましく、８０μｍ以下が更に好ましい。 The long axis of graphite (A) is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more, since it has a high capacity. The long axis of graphite (A) is preferably 100 μm or less, more preferably 90 μm or less, and even more preferably 80 μm or less, since it has excellent acceptability for lithium ions.
　本明細書において、長径は、走査型電子顕微鏡を用いて３次元的に観察したときの粒子の最長となる径を測定したもので、任意の２０個の粒子の長径の平均値とする。 In this specification, the major axis is the longest diameter of a particle when observed three-dimensionally using a scanning electron microscope, and is the average value of the major axis of any 20 particles.
　黒鉛（Ａ）の短径は、高容量となることから、０．９μｍ以上が好ましく、１．０μｍ以上がより好ましく、１．２μｍ以上が更に好ましい。黒鉛（Ａ）の短径は、リチウムイオンの受入性に優れることから、３μｍ以下が好ましく、２μｍ以下がより好ましく、１．５μｍ以下が更に好ましい。 The short axis of graphite (A) is preferably 0.9 μm or more, more preferably 1.0 μm or more, and even more preferably 1.2 μm or more, since it has a high capacity. The short axis of graphite (A) is preferably 3 μm or less, more preferably 2 μm or less, and even more preferably 1.5 μm or less, since it has excellent acceptability for lithium ions.
　本明細書において、短径は、走査型電子顕微鏡を用いて３次元的に観察したときの粒子の最短となる径を測定したもので、任意の２０個の粒子の短径の平均値とする。 In this specification, the shortest diameter is the shortest diameter of a particle when observed three-dimensionally using a scanning electron microscope, and is the average value of the shortest diameters of any 20 particles. .
　黒鉛（Ａ）のアスペクト比は、高容量となることから、２．１以上が好ましく、２．３以上がより好ましく、２．５以上が更に好ましい。黒鉛（Ａ）のアスペクト比は、リチウムイオンの受入性に優れることから、１０以下が好ましく、９以下がより好ましく、８以下が更に好ましい。 The aspect ratio of graphite (A) is preferably 2.1 or more, more preferably 2.3 or more, and even more preferably 2.5 or more, since it has a high capacity. The aspect ratio of graphite (A) is preferably 10 or less, more preferably 9 or less, and even more preferably 8 or less, since it has excellent acceptability for lithium ions.
　本明細書において、アスペクト比は、走査型電子顕微鏡を用いて３次元的に観察したときの粒子の最長となる径Ｘと、それと直交する径のうち最短となる径Ｙとにより、Ｘ／Ｙで算出したもので、任意の２０個の粒子のアスペクト比の平均値とする。 In this specification, the aspect ratio is defined by the longest diameter X of a particle when three-dimensionally observed using a scanning electron microscope, and the shortest diameter Y among the diameters orthogonal to the longest diameter, X/Y. This is the average value of the aspect ratios of any 20 particles.
　黒鉛（Ａ）の比表面積（ＳＡ）は、粒子のリチウムイオン吸蔵能力の増大により電池出力が向上することから、１ｍ２／ｇ以上が好ましく、２ｍ２／ｇ以上がより好ましく、３ｍ２／ｇ以上が更に好ましい。黒鉛（Ａ）の比表面積（ＳＡ）は、粒子の不可逆容量の増加による電池容量の減少を抑制できることから、４０ｍ２／ｇ以下が好ましく、３５ｍ２／ｇ以下がより好ましく、３０ｍ２／ｇ以下が更に好ましい。 The specific surface area (SA) of graphite (A) is preferably 1 m 2 /g or more, more preferably 2 m 2 /g or more, and 3 m 2 /g because the battery output is improved by increasing the lithium ion storage capacity of the particles. The above is more preferable. The specific surface area (SA) of graphite (A) is preferably 40 m 2 /g or less, more preferably 35 m 2 /g or less, and 30 m 2 /g or less, since it can suppress a decrease in battery capacity due to an increase in the irreversible capacity of the particles. is even more preferable.
　本明細書において、比表面積（ＳＡ）は、ＢＥＴ法により測定した値とする。
　具体的には、比表面積測定装置を用いて、試料に対して窒素流通下で１５０℃に加熱して前処理を行った後、液体窒素温度まで冷却し、大気圧に対する窒素の相対圧の値が０．３となるように正確に調整した窒素ヘリウム混合ガスを用い、ガス流動法による窒素吸着ＢＥＴ１点法により測定する。 In this specification, the specific surface area (SA) is a value measured by the BET method.
Specifically, using a specific surface area measurement device, the sample is pretreated by heating it to 150°C under nitrogen flow, then cooled to liquid nitrogen temperature, and the value of the relative pressure of nitrogen to atmospheric pressure is measured. Using a nitrogen-helium mixed gas that has been precisely adjusted so that the value is 0.3, the measurement is performed by the nitrogen adsorption BET one-point method using the gas flow method.
　黒鉛（Ａ）のタップ密度は、極板作製時のスジ引き等の工程不良を抑制でき、充填性が上がるため圧延性が良好で高密度の負極シートが形成しやすく、電極体にしたときにリチウムイオンの移動経路の屈曲度が小さくなり、粒子間の空隙の形状が整うため電解液の移動がスムーズになり急速充放電特性が向上することから、０．１ｇ／ｃｍ３以上が好ましく、０．１３ｇ／ｃｍ３以上がより好ましく、０．１５ｇ／ｃｍ３以上が更に好ましい。黒鉛（Ａ）のタップ密度は、粒子の表面や内部に適度な空間を有するため粒子が固くなり過ぎず電極プレス性に優れ、急速充放電特性や低温入出力特性に優れることから、１．０ｇ／ｃｍ３以下が好ましく、０．８ｇ／ｃｍ３以下がより好ましく、０．６ｇ／ｃｍ３以下が更に好ましい。 The tap density of graphite (A) can suppress process defects such as streaking during electrode plate production, and improves filling properties, resulting in good rollability and easy formation of a high-density negative electrode sheet, which makes it easier to form a high-density negative electrode sheet when made into an electrode body. The degree of curvature of the movement path of lithium ions is reduced and the shape of the voids between particles is adjusted, so the movement of the electrolyte becomes smooth and the rapid charging and discharging characteristics are improved . .13 g/cm 3 or more is more preferable, and 0.15 g/cm 3 or more is even more preferable. The tap density of graphite (A) is 1.0 g because the particles do not become too hard due to the appropriate space on the surface and inside of the particles and have excellent electrode pressability, as well as excellent rapid charge/discharge characteristics and low-temperature input/output characteristics. /cm 3 or less is preferable, 0.8 g/cm 3 or less is more preferable, and 0.6 g/cm 3 or less is still more preferable.
　本発明において、タップ密度は、粉体密度測定器を用い、直径１．５ｃｍ、体積容量２０ｃｍ３の円筒状タップセルに、目開き３００μｍの篩を通して、試料を落下させて、セルに満杯に充填した後、ストローク長１０ｍｍのタップを１０００回行って、そのときの体積と試料の質量から算出した密度の値とする。 In the present invention, the tap density is determined by dropping the sample into a cylindrical tap cell with a diameter of 1.5 cm and a volumetric capacity of 20 cm 3 through a sieve with an opening of 300 μm, and filling the cell to the full. After that, tapping with a stroke length of 10 mm is performed 1000 times, and the density value is calculated from the volume at that time and the mass of the sample.
　黒鉛（Ａ）のラマンＲ値は、粒子の反応面が広い方がより効率的にＬｉと反応できるため０．１以上が好ましく、０．２以上がより好ましく、０．３以上が更に好ましい。黒鉛（Ａ）のラマンＲ値はグラファイト性の高いほうが高い導電性を示し、電池には好適であることから、０．７以下が好ましく、０．６以下がより好ましく、０．５以下が更に好ましい。 The Raman R value of graphite (A) is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more, since the larger the particle reaction surface is, the more efficiently it can react with Li. The Raman R value of graphite (A) is preferably 0.7 or less, more preferably 0.6 or less, and even more preferably 0.5 or less, since the higher the graphite property, the higher the conductivity, which is suitable for batteries. preferable.
　本明細書において、ラマンＲ値は、ラマン分光法で求めたラマンスペクトルにおける１５８０ｃｍ－１付近のピークＰＡの強度ＩＡと、１３６０ｃｍ－１付近のピークＰＢの強度ＩＢとを測定し、その強度比（ＩＢ／ＩＡ）として算出した値とする。
　本明細書において、「１５８０ｃｍ－１付近」とは１５８０～１６２０ｃｍ－１の範囲を指し、「１３６０ｃｍ－１付近」とは１３５０～１３７０ｃｍ－１の範囲を指す。
　ラマンスペクトルは、ラマン分光器で測定する。具体的には、試料を測定セル内へ自然落下させることで充填し、測定セル内にアルゴンイオンレーザー光を照射しながら、測定セルをこのレーザー光と垂直な面内で回転させながら測定を行う。測定条件は、以下の通りである。
　アルゴンイオンレーザー光の波長　：５１４．５ｎｍ
　試料上のレーザーパワー　　　　　：２５ｍＷ
　分解能　　　　　　　　　　　　　：４ｃｍ－１
　測定範囲　　　　　　　　　　　　：１１００ｃｍ－１～１７３０ｃｍ－１
　ピーク強度測定、ピーク半値幅測定：バックグラウンド処理、スムージング処理（単純平均によるコンボリューション５ポイント） In this specification , the Raman R value is defined as the intensity ratio ( The value is calculated as (IB/IA).
In this specification, "near 1580 cm -1 " refers to the range of 1580 to 1620 cm -1 , and "near 1360 cm -1 " refers to the range of 1350 to 1370 cm -1 .
Raman spectra are measured with a Raman spectrometer. Specifically, the sample is filled by letting it fall naturally into the measurement cell, and the measurement is performed while irradiating the measurement cell with argon ion laser light and rotating the measurement cell in a plane perpendicular to the laser light. . The measurement conditions are as follows.
Argon ion laser light wavelength: 514.5nm
Laser power on sample: 25mW
Resolution: 4cm -1
Measurement range: 1100cm -1 ~ 1730cm -1
Peak intensity measurement, peak half-width measurement: background processing, smoothing processing (5 points of convolution using simple average)
　黒鉛（Ａ）のｄ００２値は、黒鉛が高結晶で、十分な充放電容量を有することから、３．３７Å以下が好ましく、３．３６Å以下がより好ましい。 The d002 value of graphite (A) is preferably 3.37 Å or less, more preferably 3.36 Å or less, because graphite is highly crystalline and has sufficient charge/discharge capacity.
　黒鉛（Ａ）のＬｃは、黒鉛が高結晶で、十分な充放電容量を有することから、９００Å以上が好ましく、９５０Å以上がより好ましい。 The Lc of graphite (A) is preferably 900 Å or more, more preferably 950 Å or more, since graphite is highly crystalline and has sufficient charge/discharge capacity.
　本明細書において、ｄ００２値は、学振法によるＸ線回折法により測定した格子面（００２面）の面間隔の値とする。Ｌｃは、学振法によるＸ線回折法により測定した結晶子の大きさの値とする。Ｘ線回折の測定条件は、以下とする。
　　Ｘ線：ＣｕＫα線
　　測定範囲：２０°≦２θ≦３０°
　　ステップ角度：０．０１３°
　　試料調整：０．２ｍｍの深さの試料板凹部に粉末試料を充填し平坦な試料面を作製 In this specification, the d002 value is the value of the interplanar spacing of the lattice planes (002 planes) measured by the X-ray diffraction method according to the Jakushin method. Lc is the value of the crystallite size measured by the X-ray diffraction method according to the Jakushin method. The measurement conditions for X-ray diffraction are as follows.
X-ray: CuKα ray Measurement range: 20°≦2θ≦30°
Step angle: 0.013°
Sample preparation: Fill the sample plate recess with a depth of 0.2 mm with powder sample to create a flat sample surface.
　（粒子（Ｂ））
　粒子（Ｂ）は、タンタル化合物及びセリウム化合物からなる群より選ばれる少なくとも１種を含む。粒子（Ｂ）がイオン半径の大きいタンタル化合物及びセリウム化合物からなる群より選ばれる少なくとも１種を含むことで、リチウムイオンの拡散経路を確保しつつ、電解液に対する安定性が向上するため、二次電池のサイクル特性を向上させることができる。 (Particle (B))
Particles (B) contain at least one selected from the group consisting of tantalum compounds and cerium compounds. By containing at least one kind selected from the group consisting of tantalum compounds and cerium compounds having a large ionic radius, the particles (B) secure a diffusion path for lithium ions and improve stability against the electrolyte. The cycle characteristics of the battery can be improved.
　タンタル化合物としては、例えば、五酸化タンタル、二酸化タンタル等の酸化タンタルが挙げられる。これらのタンタル化合物は、１種を単独で用いてもよく、２種以上を併用してもよい。これらのタンタル化合物の中でも、安定性に優れることから、酸化タンタルが好ましく、五酸化タンタルが好ましい。 Examples of tantalum compounds include tantalum oxides such as tantalum pentoxide and tantalum dioxide. These tantalum compounds may be used alone or in combination of two or more. Among these tantalum compounds, tantalum oxide is preferred, and tantalum pentoxide is preferred because of its excellent stability.
　タンタル化合物の結晶状態は、単結晶であってもよく、多結晶であってもよく、アモルファスであってもよい。小粒径化しやすく、レート特性に優れることから、タンタル化合物は多結晶、またはアモルファスが好ましい。 The crystalline state of the tantalum compound may be single crystal, polycrystal, or amorphous. The tantalum compound is preferably polycrystalline or amorphous because it is easy to reduce the particle size and has excellent rate characteristics.
　セリウム化合物としては、例えば、酸化セリウム（ＩＶ）、酸化セリウム（ＩＩＩ）等の酸化セリウムが挙げられる。これらのセリウム化合物は、１種を単独で用いてもよく、２種以上を併用してもよい。これらのセリウム化合物の中でも、安定性に優れることから、酸化セリウムが好ましく、酸化セリウム（ＩＶ）がより好ましい。 Examples of the cerium compound include cerium oxides such as cerium (IV) oxide and cerium (III) oxide. These cerium compounds may be used alone or in combination of two or more. Among these cerium compounds, cerium oxide is preferred, and cerium (IV) oxide is more preferred because of its excellent stability.
　セリウム化合物の結晶状態は、単結晶であってもよく、多結晶であってもよく、アモルファスであってもよい。小粒径化しやすく、レート特性に優れることから、セリウム化合物は多結晶、またはアモルファスが好ましい。 The crystalline state of the cerium compound may be single crystal, polycrystal, or amorphous. The cerium compound is preferably polycrystalline or amorphous because it is easy to reduce the particle size and has excellent rate characteristics.
　粒子（Ｂ）は、タンタル化合物の１種又は２種以上とセリウム化合物の１種又は２種以上を含むものであってもよい。 The particles (B) may contain one or more tantalum compounds and one or more cerium compounds.
　粒子（Ｂ）は、タンタル及び／又はセリウムの機能を阻害する量でなければ、タンタル及び／又はセリウム以外の他の金属元素を含んでもよい。
　他の金属元素としては、例えば、アルミニウム、カルシウム、マグネシウム、ニオブ、ユーロピウム、ハフニウム等が挙げられる。他の金属元素の含有量は、タンタル及び／又はセリウム１００ｍｏｌ％に対して、５ｍｏｌ％以下が好ましい。 Particles (B) may contain metal elements other than tantalum and/or cerium, as long as the amount does not inhibit the functions of tantalum and/or cerium.
Examples of other metal elements include aluminum, calcium, magnesium, niobium, europium, and hafnium. The content of other metal elements is preferably 5 mol% or less with respect to 100 mol% of tantalum and/or cerium.
　粒子（Ｂ）は、高容量となることから、ケイ素元素を含むことが好ましい。 It is preferable that the particles (B) contain silicon element because they have a high capacity.
　粒子（Ｂ）は、電解液に対する安定性が向上することから、ケイ素元素を含む粒子（Ｂ１）の表面にタンタル化合物及び／又はセリウム化合物を有するものが好ましい。 The particles (B) preferably have a tantalum compound and/or a cerium compound on the surface of the particles (B1) containing silicon element, since the stability against the electrolyte is improved.
　（ケイ素元素を含む粒子（Ｂ１））
　ケイ素元素を含む粒子（Ｂ１）は、ケイ素元素（Ｓｉ）を含むものであればよく、そのＳｉは、Ｓｉ単体であってもよく、Ｓｉ化合物であってもよい。
　粒子（Ｂ１）の結晶状態は、結晶であってもよく、多結晶であってもよく、アモルファスであってもよいが、小粒径化しやすく、レート特性に優れることから、多結晶、またはアモルファスが好ましい。 (Particles containing silicon element (B1))
The particles (B1) containing silicon element may be those containing silicon element (Si), and the Si may be simple Si or a Si compound.
The crystal state of the particles (B1) may be crystalline, polycrystalline, or amorphous. is preferred.
　Ｓｉ化合物としては、例えば、Ｓｉ酸化物、Ｓｉ窒化物、Ｓｉ炭化物等が挙げられる。
　具体的なＳｉ化合物としては、例えば、一般式で表すとＳｉＯｘ、ＳｉＮｘ、ＳｉＣｘ、ＳｉＺｘＯｙ（Ｚ＝Ｃ、Ｎ）等が挙げられる。高容量となることから、ＳｉＯｘが好ましい。 Examples of the Si compound include Si oxide, Si nitride, and Si carbide.
Specific Si compounds include, for example, SiOx, SiNx, SiCx, SiZxOy (Z=C, N) and the like when expressed in the general formula. SiOx is preferred because it has a high capacity.
　ＳｉＯｘは、二酸化ケイ素（ＳｉＯ２）と金属Ｓｉとを原料として得られる。 SiOx is obtained using silicon dioxide (SiO 2 ) and metal Si as raw materials.
　ｘは、二次電池の寿命を長くできることから、０より大きいことが好ましく、０．１以上がより好ましく、０．５以上が更に好ましく、０．８以上が特に好ましい。ｘは、高容量となることから、２以下が好ましく、１．８以下がより好ましく、１．５以下が更に好ましく、１．２以下が特に好ましい。 x is preferably larger than 0, more preferably 0.1 or more, even more preferably 0.5 or more, and particularly preferably 0.8 or more, since it can extend the life of the secondary battery. x is preferably 2 or less, more preferably 1.8 or less, even more preferably 1.5 or less, and particularly preferably 1.2 or less, since it results in a high capacity.
　本明細書において、ＳｉＯｘにおけるｘの値は、ＳｉＯｘの酸素量を不活性ガス雰囲気下でインパルス炉加熱抽出－ＩＲ検出法によって測定し、ＳｉＯｘのケイ素量をＩＣＰ発光分光分析法によって測定し、酸素量をケイ素量で除した値とする。 In this specification, the value of x in SiOx is determined by measuring the amount of oxygen in SiOx by impulse furnace heating extraction-IR detection method under an inert gas atmosphere, measuring the amount of silicon in SiOx by ICP emission spectrometry, The amount divided by the amount of silicon.
　ＳｉＯｘは、黒鉛（Ａ）と比較して理論容量が大きく、非晶質Ｓｉ又はナノサイズのＳｉ結晶は、リチウムイオン等のアルカリイオンの出入りがしやすく、高容量化が可能となる。 SiOx has a larger theoretical capacity than graphite (A), and amorphous Si or nano-sized Si crystals allow alkali ions such as lithium ions to enter and exit easily, making it possible to increase the capacity.
　粒子（Ｂ１）の酸素含有率は、二次電池の寿命を長くできることから、粒子（Ｂ１）１００質量％中、０．０１質量％以上が好ましく、０．０３質量％以上がより好ましく、０．０５質量％以上が更に好ましい。粒子（Ｂ１）の酸素含有率は、高容量となることから、５０質量％以下が好ましく、４５質量％以下がより好ましく、４０質量％以下が更に好ましい。 The oxygen content of the particles (B1) is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and 0.01% by mass or more, more preferably 0.03% by mass or more, based on 100% by mass of the particles (B1), since this can extend the life of the secondary battery. More preferably, the amount is 0.05% by mass or more. The oxygen content of the particles (B1) is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, since it has a high capacity.
　本明細書において、酸素含有率は、不活性ガス雰囲気下インパルス炉加熱抽出－ＩＲ検出法によって測定した値とする。 In this specification, the oxygen content is a value measured by an impulse furnace heating extraction-IR detection method under an inert gas atmosphere.
　粒子（Ｂ１）内の酸素分布状態については、表面近傍に酸素が存在してもよく、粒子内部に酸素が存在してもよく、粒子内一様に酸素が存在してもよい。二次電池の寿命を長くできることから、粒子（Ｂ１）内の酸素は、表面近傍に存在していることが好ましい。 Regarding the oxygen distribution state within the particles (B1), oxygen may be present near the surface, oxygen may be present inside the particles, or oxygen may be present uniformly within the particles. Since the life of the secondary battery can be extended, it is preferable that oxygen in the particles (B1) exist near the surface.
　粒子（Ｂ１）が結晶構造を有する場合の結晶子サイズは、電池出力が向上することから、０．０５ｎｍ以上が好ましく、０．５ｎｍ以上がより好ましく、１ｎｍ以上が更に好ましい。粒子（Ｂ１）の結晶子サイズは、二次電池の寿命を長くできることから、１００ｎｍ以下が好ましく、７０ｎｍ以下がより好ましく、５０ｎｍ以下が更に好ましい。 When the particles (B1) have a crystal structure, the crystallite size is preferably 0.05 nm or more, more preferably 0.5 nm or more, and even more preferably 1 nm or more, since the battery output is improved. The crystallite size of the particles (B1) is preferably 100 nm or less, more preferably 70 nm or less, and even more preferably 50 nm or less, since the life of the secondary battery can be extended.
　本明細書において、結晶子サイズは、広角Ｘ線回折法により観測される２θ＝２８．４°付近を中心としたＳｉ（１１１）面に帰属される回折ピークからデバイ＝シェラー法によって求めた値とする。 In this specification, the crystallite size is a value determined by the Debye-Scherrer method from a diffraction peak attributed to the Si (111) plane centered around 2θ = 28.4° observed by wide-angle X-ray diffraction. shall be.
　粒子（Ｂ１）は、市販のものをそのまま用いてもよく、力学的エネルギーを付与して粒径を調整して用いてもよい。 As the particles (B1), commercially available ones may be used as they are, or mechanical energy may be applied to adjust the particle size before use.
　粒子（Ｂ１）の製造方法は、公知の方法を用いればよいが、均一性に優れることから、二酸化ケイ素粉末と金属ケイ素粉末の混合物を昇温して発生させたＳｉＯｘガスを冷却して析出させた後、力学的エネルギーを付与して製造する方法が好ましい。力学的エネルギーの付与は、公知の方法を用いればよい。 Particles (B1) may be produced by any known method, but because of their excellent uniformity, SiOx gas generated by heating a mixture of silicon dioxide powder and metal silicon powder is precipitated by cooling. Preferably, the method is one in which mechanical energy is then applied. Mechanical energy may be applied using a known method.
　ケイ素元素を含む粒子（Ｂ１）の表面にタンタル化合物及び／又はセリウム化合物を有する粒子（Ｂ）は、化学的な反応によって粒子（Ｂ１）の表面にタンタル化合物及び／又はセリウム化合物を成長させてもよく、物理的なエネルギーを与えて粒子（Ｂ１）の表面にタンタル化合物及び／又はセリウム化合物を付着させてもよい。ケイ素元素を含む粒子（Ｂ１）表面とタンタル化合物及び／又はセリウム化合物の密着性に優れることから、タンタル化合物及び／又はセリウム化合物の原料となる化合物を含む溶液を準備し、ケイ素元素を含む粒子（Ｂ１）をこの溶液に含浸させ、ケイ素元素を含む粒子（Ｂ１）の表面にタンタル化合物及び／又はセリウム化合物を付着させて、粒子（Ｂ１）の表面をタンタル化合物及び／又はセリウム化合物で被覆する方法が好ましい。 Particles (B) having a tantalum compound and/or cerium compound on the surface of the particles (B1) containing silicon element may be obtained by growing a tantalum compound and/or cerium compound on the surface of the particle (B1) by a chemical reaction. Often, a tantalum compound and/or a cerium compound may be attached to the surface of the particles (B1) by applying physical energy. Since the surface of the particles (B1) containing the silicon element has excellent adhesion between the tantalum compound and/or the cerium compound, a solution containing a compound that is a raw material for the tantalum compound and/or the cerium compound is prepared, and the particles (B1) containing the silicon element are prepared. B1) is impregnated in this solution, a tantalum compound and/or a cerium compound is attached to the surface of the particles (B1) containing silicon element, and the surface of the particles (B1) is coated with the tantalum compound and/or the cerium compound. is preferred.
　即ち、本発明の粒子の製造方法の一態様は、このようにして、ケイ素元素を含む粒子（Ｂ１）の表面の少なくとも一部をタンタル化合物及び／又はセリウム化合物で被覆する工程を含む方法である。
　ケイ素元素を含む粒子（Ｂ１）の表面にタンタル化合物及び／又はセリウム化合物を付着させた後、加熱処理を行ってもよい。 That is, one embodiment of the method for producing particles of the present invention is a method including the step of coating at least a portion of the surface of the particles (B1) containing silicon element with a tantalum compound and/or a cerium compound. .
After attaching the tantalum compound and/or the cerium compound to the surface of the particles (B1) containing the silicon element, heat treatment may be performed.
　ケイ素元素を含む粒子（Ｂ１）の表面にセリウム化合物が被覆された本発明の第２の粒子についても、化学的な反応によって粒子（Ｂ１）の表面にセリウム化合物を成長させてもよく、物理的なエネルギーを与えて粒子（Ｂ１）の表面にセリウム化合物を付着させてもよいが、ケイ素元素を含む粒子（Ｂ１）表面とセリウム化合物の密着性に優れることから、セリウム化合物の原料となる化合物を含む溶液を準備し、ケイ素元素を含む粒子（Ｂ１）をこの溶液に含浸させ、ケイ素元素を含む粒子（Ｂ１）の表面にセリウム化合物を付着させる方法が好ましい。
　ケイ素元素を含む粒子（Ｂ１）の表面にセリウム化合物を付着させた後、加熱処理を行ってもよい。 Regarding the second particle of the present invention, in which the surface of the particle (B1) containing silicon element is coated with a cerium compound, the cerium compound may be grown on the surface of the particle (B1) by a chemical reaction, or by a physical reaction. The cerium compound may be attached to the surface of the particles (B1) by applying energy, but since the cerium compound has excellent adhesion to the surface of the particles (B1) containing the silicon element, A preferred method is to prepare a solution containing silicon, impregnate particles (B1) containing silicon element in this solution, and adhere the cerium compound to the surface of the particles (B1) containing silicon element.
After the cerium compound is attached to the surface of the particles (B1) containing silicon element, heat treatment may be performed.
　（粒子（Ｂ）の物性等）
　粒子（Ｂ）におけるタンタル元素及び／又はセリウム元素の含有量は、電解液との反応を抑制できることから、ケイ素元素１００原子部に対して、１原子部以上が好ましく、３原子部以上がより好ましく、５原子部以上が更に好ましい。粒子（Ｂ）におけるタンタル元素及び／又はセリウム元素の含有量は、相対的にケイ素元素を含む粒子（Ｂ１）の含有率が大きくなるため、本発明の粒子が高容量となることから、２５原子部以下が好ましく、２０原子部以下がより好ましく、１５原子部以下が更に好ましい。 (Physical properties of particles (B), etc.)
The content of the tantalum element and/or the cerium element in the particles (B) is preferably 1 atomic part or more, more preferably 3 atomic parts or more, based on 100 atomic parts of silicon element, since it can suppress the reaction with the electrolytic solution. , more preferably 5 atomic parts or more. The content of the tantalum element and/or the cerium element in the particles (B) is 25 atoms because the content of the particles (B1) containing the silicon element is relatively large, so that the particles of the present invention have a high capacity. The amount is preferably at most 20 atomic parts, more preferably at most 20 atomic parts, even more preferably at most 15 atomic parts.
　本明細書において、粒子（Ｂ）におけるタンタル元素及び／又はセリウム元素の含有量は、Ｘ線光電子分光装置を用い、Ｘ線源単色化Ａｌ－Ｋα、出力１５ｋＶ－２２５Ｗ、帯電子中和Ｆｉｌａｍｅｎｔ　Ｃｕｒｒｅｎｔ、　Ｆｉｌａｍｅｎｔ　ｂｉａｓ、Ｃｈａｒｇｅ　ｂａｌａｎｃｅ＝０．４３Ｖ、１Ｖ、４Ｖ、パスエネルギーをワイトスペクトル１６０ｅＶ、ナロースペクトル２０ｅＶ、測定領域７００μｍ×３００μｍ、取り出し角９０°、エネルギー補正Ｓｉ　２ｐ＝１０３．５ｅＶ（ＳｉＯ２）の条件でインジウム金属に埋め込んで測定した値とする。 In this specification, the content of tantalum element and/or cerium element in the particle (B) is determined using an X-ray photoelectron spectrometer, using an X-ray source monochromatic Al-Kα, output 15 kV-225 W, and charged electron neutralization Filament Current. , Filament bias, Charge balance = 0.43V, 1V, 4V, pass energy wide spectrum 160eV, narrow spectrum 20eV, measurement area 700μm x 300μm, extraction angle 90°, energy correction Si 2p = 103.5eV (SiO 2 ). Values measured by embedding in indium metal under the following conditions.
　粒子（Ｂ）の体積基準平均粒径（ｄ５０）は、活物質層の密度を高くできることから、０．２μｍ以上が好ましく、０．３μｍ以上がより好ましく、０．４μｍ以上が更に好ましい。粒子（Ｂ）の体積基準平均粒径（ｄ５０）は、リチウムイオンの受入性に優れることから、１０μｍ以下が好ましく、３μｍ以下がより好ましく、０．８μｍ以下が更に好ましい。 The volume-based average particle diameter (d50) of the particles (B) is preferably 0.2 μm or more, more preferably 0.3 μm or more, and even more preferably 0.4 μm or more, since the density of the active material layer can be increased. The volume-based average particle diameter (d50) of the particles (B) is preferably 10 μm or less, more preferably 3 μm or less, and even more preferably 0.8 μm or less, since it has excellent lithium ion acceptability.
　粒子（Ｂ）の最大粒径ｄｍａｘは、高容量となることから、０．３μｍ以上が好ましく、０．５μｍ以上がより好ましく、１μｍ以上が更に好ましい。粒子（Ｂ）の最大粒径ｄｍａｘは、黒鉛（Ａ）との複合化が不十分な粒子（Ｂ）を低減できることから、２０μｍ以下が好ましく、５μｍ以下がより好ましく、２μｍ以下が更に好ましい。 The maximum particle diameter dmax of the particles (B) is preferably 0.3 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more, since it provides a high capacity. The maximum particle diameter dmax of the particles (B) is preferably 20 μm or less, more preferably 5 μm or less, and even more preferably 2 μm or less, since particles (B) that are insufficiently composited with graphite (A) can be reduced.
　粒子（Ｂ）の体積基準平均粒径（ｄ５０）は、本発明の粒子を酸素の存在下で加熱して黒鉛（Ａ）を燃焼・除去させて得られた粒子（Ｂ）の体積基準平均粒径（ｄ５０）を、前記測定方法で測定すればよい。最大粒径ｄｍａｘは、体積基準平均粒径（ｄ５０）の測定の際に得られた粒度分布において、粒子が測定された最も大きい粒径の値として定義される。 The volume-based average particle diameter (d50) of the particles (B) is the volume-based average particle size of the particles (B) obtained by heating the particles of the present invention in the presence of oxygen to burn and remove graphite (A). The diameter (d50) may be measured using the measurement method described above. The maximum particle size dmax is defined as the value of the largest measured particle size of particles in the particle size distribution obtained during the measurement of the volume-based average particle size (d50).
　粒子（Ｂ）の比表面積（ＳＡ）は、リチウムイオンの受入性に優れることから、０．５ｍ２／ｇ以上が好ましく、０．８ｍ２／ｇ以上がより好ましく、１ｍ２／ｇ以上が更に好ましい。粒子（Ｂ）の比表面積（ＳＡ）は、電池出力が向上することから、１２０ｍ２／ｇ以下が好ましく、１１０ｍ２／ｇ以下がより好ましく、１００ｍ２／ｇ以下が更に好ましい。 The specific surface area (SA) of the particles (B) is preferably 0.5 m 2 /g or more, more preferably 0.8 m 2 /g or more, and still more preferably 1 m 2 /g or more, since it has excellent acceptability for lithium ions. preferable. The specific surface area (SA) of the particles (B) is preferably 120 m 2 /g or less, more preferably 110 m 2 /g or less, and even more preferably 100 m 2 /g or less, since the battery output is improved.
　（本発明の第２の粒子における粒子（Ｂ）の物性等）
　本発明の第２の粒子におけるセリウム化合物を含む粒子（Ｂ）のセリウム元素の含有量は、電解液との反応を抑制できることから、ケイ素元素１００質量部に対して、０．１質量部以上が好ましく、０．４質量部以上がより好ましく、１質量部以上が更に好ましい。粒子（Ｂ）におけるセリウム元素の含有量は、相対的にケイ素元素を含む粒子（Ｂ１）の含有率が大きくなるため、本発明の第２の粒子が高容量となることから、１０質量部以下が好ましく、８質量部以下がより好ましく、５質量部以下が更に好ましい。 (Physical properties of particles (B) in the second particles of the present invention, etc.)
The content of cerium element in the particles (B) containing a cerium compound in the second particles of the present invention is 0.1 parts by mass or more based on 100 parts by mass of silicon element, since the reaction with the electrolyte can be suppressed. It is preferably 0.4 parts by mass or more, more preferably 1 part by mass or more. The content of the cerium element in the particles (B) is 10 parts by mass or less, since the content of the particles (B1) containing the silicon element is relatively large, so that the second particles of the present invention have a high capacity. is preferable, 8 parts by mass or less is more preferable, and even more preferably 5 parts by weight or less.
　本発明の第２の粒子における粒子（Ｂ）の体積基準平均粒径（ｄ５０）は、活物質層の密度を高くできることから、０．２μｍ以上が好ましく、０．３μｍ以上がより好ましく、０．４μｍ以上が更に好ましい。粒子（Ｂ）の体積基準平均粒径（ｄ５０）は、リチウムイオンの受入性に優れることから、１０μｍ以下が好ましく、３μｍ以下がより好ましく、０．８μｍ以下が更に好ましい。 The volume-based average particle diameter (d50) of the particles (B) in the second particles of the present invention is preferably 0.2 μm or more, more preferably 0.3 μm or more, and 0.2 μm or more, more preferably 0.3 μm or more, since the density of the active material layer can be increased. More preferably, the thickness is 4 μm or more. The volume-based average particle diameter (d50) of the particles (B) is preferably 10 μm or less, more preferably 3 μm or less, and even more preferably 0.8 μm or less, since it has excellent lithium ion acceptability.
　本発明の第２の粒子における粒子（Ｂ）の最大粒径ｄｍａｘは、高容量となることから、０．３μｍ以上が好ましく、０．５μｍ以上がより好ましく、１μｍ以上が更に好ましい。粒子（Ｂ）の最大粒径ｄｍａｘは、黒鉛（Ａ）との複合化が不十分な粒子（Ｂ）を低減できることから、２０μｍ以下が好ましく、５μｍ以下がより好ましく、２μｍ以下が更に好ましい。 The maximum particle diameter dmax of the particles (B) in the second particles of the present invention is preferably 0.3 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more, since it has a high capacity. The maximum particle diameter dmax of the particles (B) is preferably 20 μm or less, more preferably 5 μm or less, and even more preferably 2 μm or less, since particles (B) that are insufficiently composited with graphite (A) can be reduced.
　本発明の第２の粒子における粒子（Ｂ）の比表面積（ＳＡ）は、リチウムイオンの受入性に優れることから、０．５ｍ２／ｇ以上が好ましく、０．８ｍ２／ｇ以上がより好ましく、１ｍ２／ｇ以上が更に好ましい。粒子（Ｂ）の比表面積（ＳＡ）は、電池出力が向上することから、１２０ｍ２／ｇ以下が好ましく、１１０ｍ２／ｇ以下がより好ましく、１００ｍ２／ｇ以下が更に好ましい。 The specific surface area (SA) of the particles (B) in the second particles of the present invention is preferably 0.5 m 2 /g or more, more preferably 0.8 m 2 /g or more, since it has excellent acceptability for lithium ions. , more preferably 1 m 2 /g or more. The specific surface area (SA) of the particles (B) is preferably 120 m 2 /g or less, more preferably 110 m 2 /g or less, and even more preferably 100 m 2 /g or less, since the battery output is improved.
　（本発明の粒子の形態）
　本発明の粒子は、粒子（Ｂ）が黒鉛（Ａ）に内包されたものであることから、粒子（Ｂ）へ電子を効率的に与えることができる。
　同様に、本発明の第３の粒子にあっても、電子の効率的な供与の観点から、粒子（Ｂ）が黒鉛（Ａ）に内包されたものであることが好ましい。 (Form of particles of the present invention)
In the particles of the present invention, since the particles (B) are encapsulated in graphite (A), electrons can be efficiently provided to the particles (B).
Similarly, in the third particle of the present invention, from the viewpoint of efficient electron donation, it is preferable that the particle (B) is encapsulated in graphite (A).
　また、本発明の粒子は、表面に炭素質物を有することが、後述の黒鉛（Ａ）と粒子（Ｂ）を複合化した際に比表面積を低減できることから好ましい。
　本発明の粒子に含まれる炭素質物については後述する。 Further, it is preferable that the particles of the present invention have a carbonaceous substance on the surface because the specific surface area can be reduced when graphite (A) and particles (B) described below are composited.
The carbonaceous substances contained in the particles of the present invention will be described later.
　本発明の粒子中の黒鉛（Ａ）の含有率は、後述の黒鉛（Ａ）と粒子（Ｂ）との複合化が容易であることから、黒鉛（Ａ）と粒子（Ｂ）の合計１００質量％中、６０質量％以上が好ましく、７０質量％以上がより好ましく、８０質量％以上が更に好ましい。本発明の粒子中の黒鉛（Ａ）の含有率は、高容量となることから、９５質量％以下が好ましく、９２質量％以下が好ましく、９０質量％以下がより好ましい。 The content of graphite (A) in the particles of the present invention is determined to be 100% by mass in total of graphite (A) and particles (B), since it is easy to composite graphite (A) and particles (B), which will be described later. %, preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. The content of graphite (A) in the particles of the present invention is preferably 95% by mass or less, preferably 92% by mass or less, and more preferably 90% by mass or less, since it has a high capacity.
　本発明の粒子中の粒子（Ｂ）の含有率は、高容量となることから、黒鉛（Ａ）と粒子（Ｂ）の合計１００質量％中、５質量％以上が好ましく、８質量％以上がより好ましく、１０質量％以上が更に好ましい。本発明の粒子中の粒子（Ｂ）の含有率は、後述の黒鉛（Ａ）と粒子（Ｂ）との複合化が容易であることから、４０質量％以下が好ましく、３０質量％以下が好ましく、２０質量％以下がより好ましい。 The content of particles (B) in the particles of the present invention is preferably 5% by mass or more, and 8% by mass or more out of the total 100% by mass of graphite (A) and particles (B), since it has a high capacity. The content is more preferably 10% by mass or more. The content of particles (B) in the particles of the present invention is preferably 40% by mass or less, and preferably 30% by mass or less, since it is easy to composite graphite (A) and particles (B), which will be described later. , more preferably 20% by mass or less.
　本発明の粒子が炭素質物を含む場合、炭素質物の含有率は、本発明の粒子の比表面積が低減し、初期充放電効率に優れることから、黒鉛（Ａ）と粒子（Ｂ）の合計１００質量部に対して、２質量部以上が好ましく、５質量部以上がより好ましく、７質量部以上が更に好ましい。炭素質物の含有率は、高容量となることから、３０質量部以下が好ましく、２５質量部以下がより好ましく、２０質量部以下が更に好ましい。 When the particles of the present invention contain a carbonaceous substance, the content of the carbonaceous substance decreases the specific surface area of the particles of the present invention and has excellent initial charge/discharge efficiency. The amount is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more. The content of the carbonaceous material is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, in order to obtain a high capacity.
　炭素質物中に、非晶質炭素質物、黒鉛化物以外に、合金化可能な金属粒子、炭素微粒子が含まれてもよい。
　炭素微粒子の形状としては、例えば、粒状、球状、鎖状、針状、繊維状、板状、鱗片状等が挙げられる。
　炭素微粒子の具体例としては、例えば、石炭微粉、気相炭素粉、カーボンブラック、ケッチェンブラック、カーボンナノファイバー等が挙げられる。これらの炭素微粒子は、１種を単独で用いてもよく、２種以上を併用してもよい。これらの炭素微粒子の中でも、低温入出力特性に優れることから、カーボンブラックが好ましい。 The carbonaceous material may contain alloyable metal particles and carbon fine particles in addition to the amorphous carbonaceous material and the graphitized material.
Examples of the shape of the carbon fine particles include granules, spheres, chains, needles, fibers, plates, and scales.
Specific examples of carbon fine particles include fine coal powder, gas phase carbon powder, carbon black, Ketjenblack, carbon nanofibers, and the like. These carbon fine particles may be used alone or in combination of two or more. Among these carbon fine particles, carbon black is preferred because it has excellent low-temperature input/output characteristics.
　（本発明の粒子の物性）
　本発明の粒子の体積基準平均粒径（ｄ５０）は、比表面積が大きくなり過ぎず、電解液に対する活性を抑制できることから、１μｍ以上が好ましく、４μｍ以上がより好ましく、６μｍ以上が更に好ましい。本発明の粒子の体積基準平均粒径（ｄ５０）は、極板製造時に筋引きや凹凸の発生を抑制できることから、５０μｍ以下が好ましく、４０μｍ以下がより好ましく、３０μｍ以下が更に好ましい。 (Physical properties of particles of the present invention)
The volume-based average particle diameter (d50) of the particles of the present invention is preferably 1 μm or more, more preferably 4 μm or more, and even more preferably 6 μm or more, since the specific surface area does not become too large and the activity against the electrolyte can be suppressed. The volume-based average particle diameter (d50) of the particles of the present invention is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less, since this can suppress the generation of streaks and unevenness during electrode plate production.
　本発明の粒子の比表面積（ＳＡ）は、粒子のリチウムイオン吸蔵能力の増大により電池出力が向上することから、０．１ｍ２／ｇ以上が好ましく、０．７ｍ２／ｇ以上がより好ましく、１ｍ２／ｇ以上が更に好ましい。本発明の粒子の比表面積（ＳＡ）は、電解液に対する活性を抑制できることから、４０ｍ２／ｇ以下が好ましく、３５ｍ２／ｇ以下がより好ましく、３０ｍ２／ｇ以下が更に好ましい。 The specific surface area (SA) of the particles of the present invention is preferably 0.1 m 2 /g or more, more preferably 0.7 m 2 /g or more, since battery output is improved by increasing the lithium ion storage capacity of the particles. More preferably, it is 1 m 2 /g or more. The specific surface area (SA) of the particles of the present invention is preferably 40 m 2 /g or less, more preferably 35 m 2 /g or less, and even more preferably 30 m 2 /g or less, since the particles can suppress activity with respect to the electrolyte.
　本発明の粒子のタップ密度は、粒子間の空隙の形状が整うため電解液の移動がスムーズになり急速充放電特性が向上することから、０．５ｇ／ｃｍ３以上が好ましく、０．６ｇ／ｃｍ３以上がより好ましく、０．８ｇ／ｃｍ３以上が更に好ましい。本発明の粒子のタップ密度は、二次電池の体積エネルギー密度に優れることから、２．２ｇ／ｃｍ３以下が好ましく、２．０ｇ／ｃｍ３以下がより好ましく、１．９ｇ／ｃｍ３以下が更に好ましい。 The tap density of the particles of the present invention is preferably 0.5 g/cm 3 or more, and 0.6 g/cm 3 or more, since the shape of the voids between particles is arranged, smoothing the movement of the electrolyte and improving rapid charge/discharge characteristics. cm 3 or more is more preferable, and 0.8 g/cm 3 or more is even more preferable. The tapped density of the particles of the present invention is preferably 2.2 g/cm 3 or less, more preferably 2.0 g/cm 3 or less, and 1.9 g/cm 3 or less, since the tap density of the particles of the present invention is excellent in the volumetric energy density of the secondary battery. More preferred.
　本発明の粒子のｄ００２値は、黒鉛が高結晶で、十分な充放電容量を有することから、３．３７Å以下が好ましく、３．３６Å以下がより好ましい。 The d002 value of the particles of the present invention is preferably 3.37 Å or less, more preferably 3.36 Å or less, because graphite is highly crystalline and has sufficient charge/discharge capacity.
　本発明の粒子のＬｃは、黒鉛が高結晶で、十分な充放電容量を有することから、９００Å以上が好ましく、９５０Å以上がより好ましい。 The Lc of the particles of the present invention is preferably 900 Å or more, more preferably 950 Å or more, since graphite is highly crystalline and has sufficient charge and discharge capacity.
　本発明の粒子のラマンＲ値は、導電性に優れることから、０．０５以上が好ましく、０．１以上がより好ましく、高容量となることから、０．４以下が好ましく、０．３５以下がより好ましい。 The Raman R value of the particles of the present invention is preferably 0.05 or more, more preferably 0.1 or more because it has excellent conductivity, and preferably 0.4 or less and 0.35 or less because it has high capacity. is more preferable.
　（本発明の粒子の製造方法）
　本発明の粒子の製造方法は、電池出力が向上することから、黒鉛（Ａ）と粒子（Ｂ）とを複合化する方法であることが好ましく、二次電池の寿命を長くできることから、黒鉛（Ａ）と粒子（Ｂ）とを球形化処理して複合化することがより好ましい。黒鉛（Ａ）と粒子（Ｂ）とを球形化処理して複合化することで、粒子（Ｂ）が黒鉛（Ａ）に内包された粒子が得られる。
　即ち、本発明の一実施形態は、黒鉛（Ａ）に、タンタル化合物及びセリウム化合物からなる群より選ばれる少なくとも１種を含む粒子（Ｂ）を内包する工程を含む粒子の製造方法である。
　また、この方法において、更に、ケイ素元素を含む粒子（Ｂ１）の表面にタンタル化合物及びセリウム化合物からなる群より選ばれる少なくとも１種を被覆する工程を含むことが好ましい。 (Method for producing particles of the present invention)
The method for producing particles of the present invention is preferably a method of compounding graphite (A) and particles (B) because it improves battery output, and graphite (A) and particles (B) are preferably composited because the life of the secondary battery can be extended. It is more preferable to subject A) and particles (B) to a spheroidization treatment to form a composite. By subjecting graphite (A) and particles (B) to a spheroidizing process to form a composite, particles in which particles (B) are encapsulated in graphite (A) can be obtained.
That is, one embodiment of the present invention is a method for producing particles including a step of encapsulating particles (B) containing at least one selected from the group consisting of tantalum compounds and cerium compounds in graphite (A).
Moreover, this method preferably further includes a step of coating the surface of the particles (B1) containing silicon element with at least one member selected from the group consisting of tantalum compounds and cerium compounds.
　黒鉛（Ａ）と粒子（Ｂ）とを球形化処理して複合化する方法は、均一性に優れることから、以下の工程（１）及び工程（２）を含む方法が好ましい。
　　工程（１）：黒鉛（Ａ）と粒子（Ｂ）とを混合する工程
　　工程（２）：工程（１）で得られた混合物に力学的エネルギーを与え球形化処理する工程 Since the method of spheroidizing graphite (A) and particles (B) to form a composite has excellent uniformity, a method including the following steps (1) and (2) is preferable.
Step (1): A step of mixing graphite (A) and particles (B). Step (2): A step of applying mechanical energy to the mixture obtained in step (1) and spheroidizing it.
　（工程（１））
　工程（１）は、黒鉛（Ａ）と粒子（Ｂ）とを混合する工程である。
　混合方法は、公知の方法を用いることができる。 (Step (1))
Step (1) is a step of mixing graphite (A) and particles (B).
A known mixing method can be used.
　（工程（２））
　工程（２）は、工程（１）で得られた混合物に力学的エネルギーを与え球形化処理する工程である。 (Step (2))
Step (2) is a step of applying mechanical energy to the mixture obtained in step (1) to form a spheroid.
　力学的エネルギーとしては、例えば、衝撃、圧縮、摩擦、せん断力等が挙げられる。これらの力学的エネルギーは、１種を単独で用いてもよく、２種以上を併用してもよい。
　力学的エネルギーを与える装置は、ハイブリダイゼーションシステムが好ましい。ハイブリダイゼーションシステムは、衝撃、圧縮、摩擦及びせん断の力学的エネルギーを与える多数のブレードを有するローターを有し、ローターの回転により大きな気流が発生し、それにより混合物中の黒鉛（Ａ）に大きな遠心力がかかり、黒鉛（Ａ）同士の衝突、黒鉛（Ａ）と壁やブレードとの衝突により、黒鉛（Ａ）と粒子（Ｂ）との複合化が効率よく進行する。 Examples of mechanical energy include impact, compression, friction, and shear force. These mechanical energies may be used alone or in combination of two or more.
The device for applying mechanical energy is preferably a hybridization system. The hybridization system has a rotor with a large number of blades that imparts mechanical energy of impact, compression, friction and shear, and the rotation of the rotor generates a large air current, which causes a large centrifugal force on the graphite (A) in the mixture. Due to the force applied, the graphite (A) collides with each other, and the graphite (A) collides with the wall or blade, so that the composite of graphite (A) and particles (B) progresses efficiently.
　ローターの周速度は、複合化の効率に優れることから、３０ｍ／秒以上が好ましく、４０ｍ／秒以上がより好ましく、５０ｍ／秒以上が更に好ましい。ローターの周速度は、衝突エネルギーによる発熱を抑制できることから、１２０ｍ／秒以下が好ましく、１１０ｍ／秒以下がより好ましく、１００ｍ／秒以下が更に好ましい。
　ローターの回転時間は、複合化の均一性に優れることから、０．５分以上が好ましく、１分以上がより好ましく、２分以上が更に好ましい。ローターの回転時間は、高容量となることから、６０分以下が好ましく、３０分以下がより好ましく、１０分以下が更に好ましい。 The circumferential speed of the rotor is preferably 30 m/sec or more, more preferably 40 m/sec or more, and even more preferably 50 m/sec or more, since the efficiency of compounding is excellent. The circumferential speed of the rotor is preferably 120 m/sec or less, more preferably 110 m/sec or less, and even more preferably 100 m/sec or less, since heat generation due to collision energy can be suppressed.
The rotation time of the rotor is preferably 0.5 minutes or more, more preferably 1 minute or more, and even more preferably 2 minutes or more, since the uniformity of compounding is excellent. The rotation time of the rotor is preferably 60 minutes or less, more preferably 30 minutes or less, and even more preferably 10 minutes or less, since the capacity is high.
　混合物中には、必要に応じて、造粒剤を添加してもよい。
　造粒剤は、公知の造粒剤を用いることができる。 A granulating agent may be added to the mixture, if necessary.
A known granulating agent can be used as the granulating agent.
　本発明の粒子の製造方法は、粒子の比表面積を制御しやすいことから、更に、以下の工程（３）を含むことが好ましい。工程（３）により、表面に炭素質物を有する本発明の粒子が得られる。
　　工程（３）：黒鉛（Ａ）と粒子（Ｂ）とを含む粒子（以下、「粒子（Ｃ）」と称す場合がある。）の表面に炭素質物を被覆する工程 The method for producing particles of the present invention preferably further includes the following step (3) because the specific surface area of the particles can be easily controlled. Through step (3), particles of the present invention having a carbonaceous substance on the surface are obtained.
Step (3): A step of coating the surface of particles (hereinafter sometimes referred to as "particles (C)") containing graphite (A) and particles (B) with a carbonaceous material.
　炭素質物は、非晶質炭素質物、黒鉛化物が挙げられるが、リチウムイオンの受入性に優れることから、非晶質炭素質物が好ましい。
　非晶質炭素質物とは、ｄ００２値が０．３４０ｎｍ以上の炭素のことをいう。
　黒鉛質物とは、ｄ００２値が０．３４０ｎｍ未満の黒鉛のことをいう。 Examples of the carbonaceous substance include amorphous carbonaceous substances and graphitized substances, but amorphous carbonaceous substances are preferable because they have excellent acceptability for lithium ions.
The amorphous carbonaceous material refers to carbon having a d002 value of 0.340 nm or more.
Graphite material refers to graphite having a d002 value of less than 0.340 nm.
　粒子（Ｃ）の表面に非晶質炭素質物又は黒鉛質物を被覆する方法は、被覆効率に優れることから、粒子と非晶質炭素質物前駆体又は黒鉛質物前駆体とを混合し、非酸化性雰囲気下で加熱して、非晶質炭素質物前駆体を非晶質炭素化又は黒鉛質物前駆体を黒鉛化する方法が好ましい。 The method of coating the surface of the particles (C) with an amorphous carbonaceous substance or a graphite substance has excellent coating efficiency, and therefore, the particles are mixed with an amorphous carbonaceous substance precursor or a graphite substance precursor, and a non-oxidizing Preferred is a method in which the amorphous carbonaceous material precursor is amorphous carbonized or the graphitic material precursor is graphitized by heating in an atmosphere.
　粒子（Ｃ）と非晶質炭素質物前駆体又は黒鉛質物前駆体との混合方法としては、例えば、粒子（Ｃ）と非晶質炭素質物前駆体又は黒鉛質物前駆体とをミキサーやニーダーを用いて混合する方法、非晶質炭素質物前駆体又は黒鉛質物前駆体を溶解した溶液に粒子（Ｃ）を添加して溶媒を除去する方法等が挙げられる。これらの方法の中でも、１ｎｍ～４ｎｍの微細孔を効率的に低減できることから、粒子（Ｃ）と非晶質炭素質物前駆体又は黒鉛質物前駆体とをミキサーやニーダーを用いて混合する方法が好ましい。 As a method of mixing the particles (C) and the amorphous carbonaceous material precursor or the graphite material precursor, for example, the particles (C) and the amorphous carbonaceous material precursor or the graphite material precursor are mixed using a mixer or a kneader. Examples include a method in which the particles (C) are added to a solution in which an amorphous carbonaceous material precursor or a graphite material precursor is dissolved and the solvent is removed. Among these methods, a method of mixing particles (C) and an amorphous carbonaceous material precursor or a graphite material precursor using a mixer or a kneader is preferable because it can efficiently reduce micropores of 1 nm to 4 nm. .
　混合後の加熱時の雰囲気は、非酸化性雰囲気下であれば特に限定されないが、二次電池の初期効率に優れることから、窒素、アルゴン、二酸化炭素が好ましく、窒素がより好ましい。
　非酸化性雰囲気の酸素濃度は、二次電池の初期効率に優れることから、１体積％以下が好ましく、０．１体積％以下がより好ましい。 The atmosphere during heating after mixing is not particularly limited as long as it is a non-oxidizing atmosphere, but nitrogen, argon, and carbon dioxide are preferable, and nitrogen is more preferable because the initial efficiency of the secondary battery is excellent.
The oxygen concentration of the non-oxidizing atmosphere is preferably 1% by volume or less, more preferably 0.1% by volume or less, since the initial efficiency of the secondary battery is excellent.
　加熱温度は、非晶質炭素質物前駆体の非晶質炭素化と黒鉛質物前駆体の黒鉛化とで異なる。
　非晶質炭素質物前駆体を非晶質炭素化する場合の加熱温度は、黒鉛の結晶構造と同等の結晶構造に達しない温度であれば特に限定されないが、５００℃以上が好ましく、６００℃以上がより好ましく、７００℃以上が更に好ましく、２０００℃以下が好ましく、１８００℃以下がより好ましく、１６００℃以下が更に好ましい。
　黒鉛質物前駆体を黒鉛化する場合の加熱温度は、黒鉛の結晶構造と同等の結晶構造に達する温度であれば特に限定されないが、２１００℃以上が好ましく、２５００℃以上がより好ましく、２７００℃以上が更に好ましく、３３００℃以下が好ましく、３２００℃以下がより好ましく、３１００℃以下が更に好ましい。 The heating temperature is different for amorphous carbonization of the amorphous carbonaceous material precursor and graphitization of the graphitic material precursor.
The heating temperature for amorphous carbonizing the amorphous carbonaceous material precursor is not particularly limited as long as it does not reach a crystal structure equivalent to that of graphite, but is preferably 500°C or higher, and 600°C or higher. is more preferable, 700°C or higher is still more preferable, 2000°C or lower is preferable, 1800°C or lower is more preferable, and even more preferably 1600°C or lower.
The heating temperature when graphitizing the graphite substance precursor is not particularly limited as long as it reaches a crystal structure equivalent to that of graphite, but is preferably 2100°C or higher, more preferably 2500°C or higher, and 2700°C or higher. is more preferable, 3300°C or less is preferable, 3200°C or less is more preferable, and even more preferably 3100°C or less.
　加熱時間は、二次電池に適した黒鉛化度になることから、０．１時間以上が好ましく、１時間以上がより好ましい。加熱時間は、黒鉛（Ａ）と粒子（Ｂ）の反応による副生物を抑制できることから、１０００時間以下が好ましく、１００時間以下がより好ましい。 The heating time is preferably 0.1 hour or more, more preferably 1 hour or more, since the degree of graphitization is suitable for a secondary battery. The heating time is preferably 1000 hours or less, more preferably 100 hours or less, since byproducts due to the reaction between graphite (A) and particles (B) can be suppressed.
　非晶質炭素質物前駆体や黒鉛質物前駆体としては、例えば、タール、ピッチ、ナフタレンやアントラセン等の芳香族炭化水素類、フェノール樹脂やポリビニルアルコール樹脂等の熱可塑性樹脂類等が挙げられる。これらの前駆体は、１種を単独で用いてもよく、２種以上を併用してもよい。これらの前駆体の中でも、炭素構造が発達しやすく、少ない量で被覆できることから、タール、ピッチ、芳香族炭化水素類が好ましく、残炭率５０％以上のものがより好ましく、残炭率６０％以上のものが更に好ましい。 Examples of the amorphous carbonaceous material precursor and graphite material precursor include tar, pitch, aromatic hydrocarbons such as naphthalene and anthracene, and thermoplastic resins such as phenol resin and polyvinyl alcohol resin. These precursors may be used alone or in combination of two or more. Among these precursors, tar, pitch, and aromatic hydrocarbons are preferable because they allow carbon structures to develop easily and can be coated with a small amount, and those with a residual carbon content of 50% or more are more preferable, and those with a residual carbon content of 60% are preferable. The above are more preferred.
　非晶質炭素質物前駆体や黒鉛質物前駆体中の灰分は、二次電池の寿命を長くできることから、非晶質炭素質物前駆体や黒鉛質物前駆体１００質量％中、０．００００１質量％以上が好ましく、１質量％以下が好ましく、０．５質量％以下がより好ましく、０．１質量％以下が更に好ましい。 Since the ash content in the amorphous carbonaceous material precursor or graphite material precursor can extend the life of the secondary battery, it should be 0.00001% by mass or more in 100% by mass of the amorphous carbonaceous material precursor or graphite material precursor. The content is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less.
　非晶質炭素質物前駆体や黒鉛質物前駆体中の金属不純物含有率は、二次電池の寿命を長くできることから、非晶質炭素質物前駆体や黒鉛質物前駆体１００質量％中、０．１質量ｐｐｍ以上が好ましく、１０００質量ｐｐｍ以下が好ましく、５００質量ｐｐｍ以下がより好ましく、１００質量ｐｐｍ以下が更に好ましい。 The metal impurity content in the amorphous carbonaceous material precursor or graphite material precursor is 0.1% by mass of the amorphous carbonaceous material precursor or graphite material precursor, since this can extend the life of the secondary battery. It is preferably at least 1000 ppm by mass, more preferably at most 500 ppm by mass, and even more preferably at most 100 ppm by mass.
　本明細書において、金属不純物含有率は、非晶質炭素質物前駆体や黒鉛質物前駆体中のＦｅ、Ａｌ、Ｓｉ、Ｃａの合計含有率を残炭率で除した値とする。 In this specification, the metal impurity content is the value obtained by dividing the total content of Fe, Al, Si, and Ca in the amorphous carbonaceous material precursor or graphite material precursor by the residual carbon percentage.
　非晶質炭素質物前駆体や黒鉛質物前駆体中のＱｉ（キノリン不溶分）は、二次電池の寿命を長くできることから、非晶質炭素質物前駆体や黒鉛質物前駆体１００質量％中、５質量％以下が好ましく、３質量％以下がより好ましい。 Qi (quinoline insoluble content) in the amorphous carbonaceous material precursor and graphite material precursor can extend the life of the secondary battery, so it is It is preferably at most 3% by mass, more preferably at most 3% by mass.
　本発明の粒子は、体積基準平均粒径を所望の範囲にするため、必要に応じて、粉砕、解砕、分級を行ってもよい。
　粉砕、解砕、分級は、公知の方法を用いることができる。 The particles of the present invention may be pulverized, crushed, and classified as necessary in order to adjust the volume-based average particle size to a desired range.
For pulverization, crushing, and classification, known methods can be used.
　（負極の製造方法）
　本発明の負極の製造方法は、集電体上に、本発明の粒子を塗布する工程を含む。
　本発明の負極の製造方法により製造される負極（以下、「本発明の負極」と称す場合がある。）は、集電体と該集電体上に形成された活物質層とを含み、活物質層が、本発明の粒子を含む。本発明の粒子が、負極の活物質としての作用効果を有する。 (Manufacturing method of negative electrode)
The method for producing a negative electrode of the present invention includes a step of applying particles of the present invention onto a current collector.
The negative electrode manufactured by the negative electrode manufacturing method of the present invention (hereinafter sometimes referred to as "the negative electrode of the present invention") includes a current collector and an active material layer formed on the current collector, The active material layer contains particles of the present invention. The particles of the present invention have the effect of functioning as a negative electrode active material.
　本発明の負極の製造方法は、集電体上に活物質層が形成できれば特に限定されないが、均一性に優れることから、本発明の粒子とバインダとを配合したスラリーを集電体上に塗布して乾燥する方法が好ましい。スラリーには、更に、増粘剤を配合してもよい。 The method for producing the negative electrode of the present invention is not particularly limited as long as an active material layer can be formed on the current collector, but since it has excellent uniformity, a slurry containing the particles of the present invention and a binder is coated on the current collector. A method of drying is preferred. The slurry may further contain a thickener.
　本発明の粒子とバインダとを配合したスラリーを集電体上に塗布して乾燥した後に、加圧して集電体上に形成された活物質層の密度を高め、活物質層の単位体積あたりの電池容量を大きくすることが好ましい。 After applying a slurry containing the particles of the present invention and a binder onto a current collector and drying it, pressure is applied to increase the density of the active material layer formed on the current collector. It is preferable to increase the battery capacity of the battery.
　活物質層の密度は、単位体積あたりの電池の容量の低下を抑制できることから、１．５ｇ／ｃｍ３以上が好ましく、１．６ｇ／ｃｍ３以上がより好ましく、レート特性の低下を抑制できることから、２．０ｇ／ｃｍ３以下が好ましく、１．９ｇ／ｃｍ３以下がより好ましい。 The density of the active material layer is preferably 1.5 g/cm 3 or more, more preferably 1.6 g/cm 3 or more because it can suppress a decrease in battery capacity per unit volume, and it can suppress a decrease in rate characteristics. , 2.0 g/cm 3 or less is preferable, and 1.9 g/cm 3 or less is more preferable.
　（二次電池の製造方法）
　本発明の二次電池の製造方法は、正極、負極及び電解質を含む二次電池の製造方法であって、負極が、本発明の製造方法により得られた本発明の負極である製造方法である。
　正極及び本発明の負極は、リチウムイオンを吸蔵及び放出可能であることが好ましい。 (Method for manufacturing secondary batteries)
The method for manufacturing a secondary battery of the present invention is a method for manufacturing a secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode is the negative electrode of the present invention obtained by the manufacturing method of the present invention. .
The positive electrode and the negative electrode of the present invention are preferably capable of intercalating and deintercalating lithium ions.
　（正極）
　正極は、公知の正極を用いることができる。 (positive electrode)
A known positive electrode can be used as the positive electrode.
　（電解質）
　電解質は、公知の電解質を用いることができる。 (Electrolytes)
A known electrolyte can be used as the electrolyte.
　（セパレータ）
　二次電池は、正極と負極との間にセパレータを介在させることが好ましい。
　セパレータは、公知のセパレータを用いることができる。 (Separator)
In the secondary battery, it is preferable that a separator is interposed between the positive electrode and the negative electrode.
A known separator can be used as the separator.
　（用途）
　本発明の粒子は、二次電池のサイクル特性向上効果に優れることから、二次電池の負極の活物質として好適に用いることができ、非水系二次電池の負極の活物質としてより好適に用いることができ、リチウムイオン二次電池の負極の活物質として特に好適に用いることができる。 (Application)
Since the particles of the present invention have an excellent effect of improving cycle characteristics of secondary batteries, they can be suitably used as an active material for a negative electrode of a secondary battery, and are more suitably used as an active material for a negative electrode of a non-aqueous secondary battery. It can be particularly suitably used as an active material for a negative electrode of a lithium ion secondary battery.
　以下、実施例を用いて本発明を更に具体的に説明する。本発明は、その要旨を逸脱しない限り、以下の実施例の記載に限定されるものではない。 Hereinafter, the present invention will be explained in more detail using Examples. The present invention is not limited to the description of the following examples unless it departs from the gist thereof.
　（体積基準平均粒径の測定方法）
　界面活性剤であるポリオキシエチレンソルビタンモノラウレート（商品名「ツィーン２０」）の０．２質量％水溶液１０ｍＬに、試料０．０１ｇを懸濁させ、レーザー回折／散乱式粒度分布測定装置（機種名「ＬＡ－９２０」、株式会社堀場製作所製）に導入し、２８ｋＨｚの超音波を出力６０Ｗで１分間照射した後、前記測定装置における体積基準のメジアン径を測定し、体積基準のメジアン径を体積基準平均粒径とした。 (Measurement method of volume-based average particle diameter)
0.01 g of the sample was suspended in 10 mL of a 0.2% by mass aqueous solution of polyoxyethylene sorbitan monolaurate (trade name "Tween 20"), which is a surfactant, and a laser diffraction/scattering particle size distribution analyzer (model ``LA-920'' (manufactured by Horiba, Ltd.) and irradiated with 28kHz ultrasonic waves at an output of 60W for 1 minute, the volume-based median diameter of the measurement device was measured, and the volume-based median diameter was measured. It was defined as the volume-based average particle diameter.
　（ｄ９０の測定方法）
　上記体積基準平均粒径の測定で得られた粒度分布における小さい粒子側から累積９０％に相当する粒径をｄ９０とした。 (Measurement method of d90)
The particle size corresponding to 90% cumulatively from the small particle side in the particle size distribution obtained by measuring the volume-based average particle size was defined as d90.
　（比表面積の測定方法）
　比表面積測定装置（機種名「マックソーブＨＭ　Ｍｏｄｅｌ－１２１０型」、株式会社マウンテック製）を用いて、試料に対して窒素流通下で１５０℃に加熱して前処理を行った後、液体窒素温度まで冷却し、大気圧に対する窒素の相対圧の値が０．３となるように正確に調整した窒素ヘリウム混合ガスを用い、ガス流動法による窒素吸着ＢＥＴ１点法により比表面積を測定した。 (Method of measuring specific surface area)
Using a specific surface area measuring device (model name "MacSorb HM Model-1210", manufactured by Mountec Co., Ltd.), the sample was pretreated by heating to 150 °C under nitrogen flow, and then heated to liquid nitrogen temperature. Using a cooled nitrogen-helium mixed gas that was accurately adjusted so that the relative pressure of nitrogen to atmospheric pressure was 0.3, the specific surface area was measured by the nitrogen adsorption BET one-point method using the gas flow method.
　（タップ密度の測定方法）
　粉体密度測定器（機種名「タップデンサーＫＹＴ－５０００」、株式会社セイシン企業製）を用い、直径１．２ｃｍ、体積容量２０ｃｍ３の円筒状タップセルに、目開き３００μｍの篩を通して、試料を落下させて、セルに満杯に充填した後、ストローク長１０ｍｍのタップを１０００回行って、そのときの体積と試料の質量から算出した密度の値をタップ密度とした。 (Measurement method of tap density)
Using a powder density measuring device (model name: "Tap Denser KYT-5000", manufactured by Seishin Enterprise Co., Ltd.), the sample was dropped through a sieve with an opening of 300 μm into a cylindrical tap cell with a diameter of 1.2 cm and a volumetric capacity of 20 cm 3 . After filling the cell to its full capacity, tapping with a stroke length of 10 mm was performed 1000 times, and the density value calculated from the volume at that time and the mass of the sample was taken as the tapped density.
　（ラマンＲ値の測定方法）
　堀場製作所社製「ＬａｂＲＡＭ－ＨＲ　Ｅｖｏｌｕｔｉｏｎ」を用い、アルゴンイオンレーザー光を用いたラマンスペクトル分析において、１５８０ｃｍ－１付近のピークＰＡの強度ＩＡ、１３６０ｃｍ－１付近のピークＰＢの強度ＩＢを測定し、その強度の比＝ＩＢ／ＩＡを求めた。
　試料の調製にあたっては、粉末状態のものを自然落下によりセルに充填した。セル内のサンプル表面にアルゴンイオンレーザー光を照射しながら、セルをレーザー光と垂直な面内で回転させて下記条件で測定を行った。
　アルゴンイオンレーザー光の波長　：５１４．５ｎｍ
　試料上のレーザーパワー　　　　　：２５ｍＷ
　分解能　　　　　　　　　　　　　：４ｃｍ－１
　測定範囲　　　　　　　　　　　　：１１００ｃｍ－１～１７３０ｃｍ－１
　ピーク強度測定、ピーク半値幅測定：バックグラウンド処理、スムージング処理（単純平均によるコンボリューション５ポイント） (Measurement method of Raman R value)
In Raman spectrum analysis using argon ion laser light using "LabRAM-HR Evolution" manufactured by Horiba, the intensity IA of the peak PA near 1580 cm -1 and the intensity IB of the peak PB near 1360 cm -1 were measured, The intensity ratio=IB/IA was determined.
To prepare the sample, the powder was filled into a cell by gravity. While irradiating the sample surface within the cell with argon ion laser light, the cell was rotated in a plane perpendicular to the laser light and measurements were performed under the following conditions.
Argon ion laser light wavelength: 514.5nm
Laser power on sample: 25mW
Resolution: 4cm -1
Measurement range: 1100cm -1 ~ 1730cm -1
Peak intensity measurement, peak half-width measurement: background processing, smoothing processing (5 points of convolution using simple average)
　（タンタル元素の含有量とタンタル酸化物の種類の測定方法）
　製造例２～３で得られた粒子（Ｂ－１）及び（Ｂ－２）について、Ｘ線光電子分光法（ＸＰＳ）により、タンタル元素の含有量とタンタル酸化物の種類を確認した。
　測定条件は、Ｘ線光電子分光装置（機種名「ＫＲＡＴＯＳ　ＵＬＴＲＡ２」、株式会社島津製作所）を用い、Ｘ線源単色化Ａｌ－Ｋα、出力１５ｋＶ－２２５Ｗ、帯電子中和Ｆｉｌａｍｅｎｔ　Ｃｕｒｒｅｎｔ、　Ｆｉｌａｍｅｎｔ　ｂｉａｓ、Ｃｈａｒｇｅ　ｂａｌａｎｃｅ＝０．４３Ｖ、１Ｖ、４Ｖ、パスエネルギーをワイトスペクトル１６０ｅＶ、ナロースペクトル２０ｅＶ、測定領域７００μｍ×３００μｍ、取り出し角９０°、エネルギー補正Ｓｉ　２ｐ＝１０３．５ｅＶ（ＳｉＯ２）とし、インジウム金属に埋め込んでサンプリングした。 (Method for measuring tantalum element content and tantalum oxide type)
Regarding particles (B-1) and (B-2) obtained in Production Examples 2 and 3, the content of tantalum element and the type of tantalum oxide were confirmed by X-ray photoelectron spectroscopy (XPS).
The measurement conditions were an X-ray photoelectron spectrometer (model name "KRATOS ULTRA2", Shimadzu Corporation), X-ray source monochromatic Al-Kα, output 15 kV-225 W, band electron neutralization Filament Current, Filament bias, Charge. Balance = 0.43V, 1V, 4V, pass energy wide spectrum 160eV, narrow spectrum 20eV, measurement area 700μm x 300μm, extraction angle 90°, energy correction Si 2p = 103.5eV (SiO 2 ), embedded in indium metal. sampled at.
　（セリウム元素の含有量とセリウム化合物の種類の測定方法）
　実施例３～５で得られた粒子（Ｂ－３）～（Ｂ－５）について、Ｘ線光電子分光法（ＸＰＳ）により、セリウム元素の含有量とセリウム化合物の種類を確認した。
　測定条件は、Ｘ線光電子分光装置（機種名「ＫＲＡＴＯＳ　ＵＬＴＲＡ２」、株式会社島津製作所）を用い、Ｘ線源単色化Ａｌ－Ｋα、出力１５ｋＶ－２２５Ｗ、帯電子中和Ｆｉｌａｍｅｎｔ　Ｃｕｒｒｅｎｔ、　Ｆｉｌａｍｅｎｔ　ｂｉａｓ、Ｃｈａｒｇｅ　ｂａｌａｎｃｅ＝０．４３Ｖ、１Ｖ、４Ｖ、パスエネルギーをワイトスペクトル１６０ｅＶ、ナロースペクトル２０ｅＶ、測定領域７００μｍ×３００μｍ、取り出し角９０°、エネルギー補正Ｓｉ　２ｐ＝１０３．５ｅＶ（ＳｉＯ２）とし、インジウム金属に埋め込んでサンプリングした。 (Method for measuring the content of cerium element and the type of cerium compound)
Regarding particles (B-3) to (B-5) obtained in Examples 3 to 5, the content of cerium element and the type of cerium compound were confirmed by X-ray photoelectron spectroscopy (XPS).
The measurement conditions were an X-ray photoelectron spectrometer (model name "KRATOS ULTRA2", Shimadzu Corporation), X-ray source monochromatic Al-Kα, output 15 kV-225 W, band electron neutralization Filament Current, Filament bias, Charge. Balance = 0.43V, 1V, 4V, pass energy wide spectrum 160eV, narrow spectrum 20eV, measurement area 700μm x 300μm, extraction angle 90°, energy correction Si 2p = 103.5eV (SiO 2 ), embedded in indium metal. sampled at.
　（初期容量・容量維持率・充放電効率の測定方法）
　実施例及び比較例で得られた粒子１００質量部、アセチレンブラック２．６質量部、カルボキシメチルセルロース１．６質量部及びスチレンブタジエンゴム４８質量％水性ディスパージョン３．３質量部を、ハイブリダイズミキサーを用いて混練し、スラリーを得た。
　得られたスラリーを、集電体である厚さ２０μｍの銅箔上に、目付け７～８ｍｇ／ｃｍ２付着するように塗布し、乾燥させた。その後、活物質層の密度が１．６～１．７ｇ／ｃｍ３になるよう、ロードセル付きの２５０ｍｍφロールプレスにてロールプレスし、直径１２．５ｍｍの円形状に打ち抜き、９０℃で８時間真空乾燥し、評価用の負極を得た。
　得られた負極と、対極としてリチウム箔とを、電解液を含浸させたセパレータを介して重ねて、充放電試験用の電池を得た。電解液として、エチレンカーボネート／エチルメチルカーボネート／モノフルオロエチレンカーボネート＝３０／６０／１０（体積比）の混合液に、ＬｉＰＦ６を１ｍｏｌ／Ｌとなるように溶解させたものを用いた。
　まず、０．０８ｍＡ／ｃｍ２の電流密度で前記充放電試験用の電池の電圧が５ｍＶになるまで充電し、更に、５ｍＶの一定電圧で電流値が０．０３ｍＡ／ｃｍ２になるまで充電し、負極中にリチウムをドープした後、０．２ｍＡ／ｃｍ２の電流密度で前記電池の電圧が１．５Ｖになるまで放電を行った（初期１サイクル目）。その後、充電時の電流密度を０．２ｍＡ／ｃｍ２、放電時の電流密度を０．３ｍＡ／ｃｍ２としたこと以外は、上記と同様の条件で４回、充電と放電を繰り返した（初期２サイクル目～初期５サイクル目）。評価用の負極にリチウムがドープされる方向に電流を流すことを「充電」、評価用の負極からリチウムが脱ドープされる方向に電流を流すことを「放電」とした。
　初期放電容量（ｍＡｈ／ｇ）は、負極質量から負極と同面積に打ち抜いた銅箔の質量を差し引くことで負極活物質質量を算出し、初期５サイクル目の放電容量を負極活物質質量で除して算出した。
　１ｍＡ／ｃｍ２の電流密度で前記初期充放電後の電池の電圧が５ｍＶになるまで充電し、更に、５ｍＶの一定電圧で電流値が０．１ｍＡ／ｃｍ２になるまで充電し、負極中にリチウムをドープした後、１ｍＡ／ｃｍ２の電流密度で前記電池の電圧が１．５Ｖになるまで放電を行った（１サイクル目）。その後、１サイクル目と同じ条件で９回充電と放電を繰り返した（２サイクル目～１０サイクル目）。
　１０サイクル目の容量維持率（％）は、下記式（１）により算出した。
　　１０サイクル目の容量維持率（％）＝｛１０サイクル目の放電容量（ｍＡｈ）／１サイクル目の充電容量（ｍＡｈ）｝×１００　　　（１）
　１０サイクル目の充放電効率（％）は、下記式（２）により算出した。
　　１０サイクル目の充放電効率（％）＝｛１０サイクル目の放電容量（ｍＡｈ）／１０サイクル目の充電容量（ｍＡｈ）｝×１００　　　（２） (Measurement method of initial capacity, capacity retention rate, charge/discharge efficiency)
100 parts by mass of the particles obtained in Examples and Comparative Examples, 2.6 parts by mass of acetylene black, 1.6 parts by mass of carboxymethyl cellulose, and 3.3 parts by mass of a 48% by mass aqueous dispersion of styrene-butadiene rubber were added to a hybridization mixer. A slurry was obtained.
The obtained slurry was applied onto a 20 μm thick copper foil serving as a current collector so that the coating weight was 7 to 8 mg/cm 2 and dried. Thereafter, the active material layer was roll pressed using a 250 mmφ roll press equipped with a load cell so that the density of the active material layer was 1.6 to 1.7 g/cm 3 , punched out into a circular shape with a diameter of 12.5 mm, and vacuumed at 90°C for 8 hours. It was dried to obtain a negative electrode for evaluation.
The obtained negative electrode and a lithium foil as a counter electrode were stacked with a separator impregnated with an electrolytic solution interposed therebetween to obtain a battery for a charge/discharge test. The electrolytic solution used was a mixture of ethylene carbonate/ethyl methyl carbonate/monofluoroethylene carbonate = 30/60/10 (volume ratio) in which LiPF 6 was dissolved at a concentration of 1 mol/L.
First, the battery for charge/discharge test was charged at a current density of 0.08 mA/cm 2 until the voltage reached 5 mV, and then at a constant voltage of 5 mV until the current value reached 0.03 mA/cm 2 . After doping lithium into the negative electrode, discharging was performed at a current density of 0.2 mA/cm 2 until the voltage of the battery reached 1.5 V (initial first cycle). Thereafter, charging and discharging were repeated four times under the same conditions as above, except that the current density during charging was 0.2 mA/cm 2 and the current density during discharging was 0.3 mA/cm 2 (initial 2nd cycle to initial 5th cycle). ``Charging'' refers to passing a current in a direction in which lithium is doped into the negative electrode for evaluation, and ``discharging'' refers to passing a current in a direction in which lithium is dedoped from the negative electrode for evaluation.
The initial discharge capacity (mAh/g) is calculated by subtracting the mass of the copper foil punched to the same area as the negative electrode from the mass of the negative electrode, and then dividing the discharge capacity at the initial 5th cycle by the mass of the negative electrode active material. It was calculated by
The battery was charged at a current density of 1 mA/cm 2 until the voltage of the battery after the initial charging and discharging reached 5 mV, and further charged at a constant voltage of 5 mV until the current value reached 0.1 mA/cm 2 . After doping with lithium, the battery was discharged at a current density of 1 mA/cm 2 until the voltage of the battery reached 1.5 V (first cycle). Thereafter, charging and discharging were repeated 9 times under the same conditions as the first cycle (2nd cycle to 10th cycle).
The capacity retention rate (%) at the 10th cycle was calculated using the following formula (1).
10th cycle capacity retention rate (%) = {10th cycle discharge capacity (mAh)/1st cycle charge capacity (mAh)} x 100 (1)
The charge/discharge efficiency (%) at the 10th cycle was calculated using the following formula (2).
10th cycle charge/discharge efficiency (%) = {10th cycle discharge capacity (mAh)/10th cycle charge capacity (mAh)}×100 (2)
　［製造例１：ケイ素元素を含む粒子（Ｂ１－１）の製造］
　二酸化ケイ素粉末と金属ケイ素粉末の混合物を減圧下、１０００℃以上に昇温して発生させたＳｉＯｘガスを冷却して析出させた後、粗粉砕工程を経ることで得たＳｉＯｘ粉末をボールミルで乾式粉砕することにより、ケイ素元素を含む粒子（Ｂ１－１）を製造した。 [Production Example 1: Production of particles containing silicon element (B1-1)]
A mixture of silicon dioxide powder and metal silicon powder is heated to 1000°C or higher under reduced pressure, the generated SiOx gas is cooled and precipitated, and then the SiOx powder obtained by passing through a coarse pulverization process is dry-processed using a ball mill. Particles containing silicon element (B1-1) were produced by pulverization.
　［製造例２：粒子（Ｂ－１）の製造］
　酢酸１．６質量部とエタノール６５．４質量部とを混合した溶液に、タンタル（Ｖ）エトキシド３．６質量部を加え、２５℃で３０分撹拌後、酢酸８．６質量部とエタノール５１．４質量部とを混合した溶液を滴下し、ジエタノールアミン４．４質量部とエタノール４０質量部とを混合した溶液を滴下し、２５℃で３０分撹拌し、タンタル酸化物のゾル溶液を得た。
　ケイ素元素を含む粒子（Ｂ１－１）１００質量部をエタノール１２４．４質量部に分散させた懸濁液に、得られたタンタル酸化物のゾル溶液を滴下し、２５℃で６０分撹拌後、６０℃減圧下で溶媒を留去し、粉末を得た。
　得られた粉末を、１２０℃で６時間加熱し、更に、空気雰囲気下で５００℃で１時間加熱した。その後、得られた粉体をメノウで解砕し、ケイ素元素を含む粒子（Ｂ１－１）の表面にタンタル酸化物を有する粒子（Ｂ－１）を得た。
　得られた粒子（Ｂ－１）は、ケイ素元素１００原子部に対して、タンタル元素１３原子部を含有するものであり、タンタル酸化物が五酸化タンタルを含むことが確認された。 [Production Example 2: Production of particles (B-1)]
3.6 parts by mass of tantalum (V) ethoxide was added to a solution of 1.6 parts by mass of acetic acid and 65.4 parts by mass of ethanol, and after stirring at 25°C for 30 minutes, 8.6 parts by mass of acetic acid and 51 parts by mass of ethanol were added. A solution containing 4.4 parts by mass of diethanolamine and 40 parts by mass of ethanol was added dropwise, and the mixture was stirred at 25°C for 30 minutes to obtain a sol solution of tantalum oxide. .
The obtained sol solution of tantalum oxide was added dropwise to a suspension of 100 parts by mass of particles (B1-1) containing silicon element dispersed in 124.4 parts by mass of ethanol, and after stirring at 25 ° C. for 60 minutes, The solvent was distilled off under reduced pressure at 60°C to obtain a powder.
The obtained powder was heated at 120°C for 6 hours and further heated at 500°C for 1 hour in an air atmosphere. Thereafter, the obtained powder was crushed with an agate to obtain particles (B-1) containing tantalum oxide on the surface of particles (B1-1) containing silicon element.
The obtained particles (B-1) contained 13 atomic parts of tantalum element per 100 atomic parts of silicon element, and it was confirmed that the tantalum oxide contained tantalum pentoxide.
　［製造例３：粒子（Ｂ－２）の製造］
　空気雰囲気下で５００℃で１時間加熱したことを、窒素雰囲気下で５００℃で１時間加熱したことに変更したこと以外は、製造例２と同様に操作を行い、粒子（Ｂ－２）を得た。
　得られた粒子（Ｂ－２）は、ケイ素元素１００原子部に対して、タンタル元素を１１原子部含有するものであり、タンタル酸化物が五酸化タンタルを含むことが確認された。 [Production Example 3: Production of particles (B-2)]
Particles (B-2) were produced in the same manner as in Production Example 2, except that heating at 500°C for 1 hour in an air atmosphere was changed to heating at 500°C for 1 hour in a nitrogen atmosphere. Obtained.
The obtained particles (B-2) contained 11 atomic parts of tantalum element per 100 atomic parts of silicon element, and it was confirmed that the tantalum oxide contained tantalum pentoxide.
　［実施例１］
　鱗片状黒鉛（Ａ－１）（体積基準平均粒径：１１．１μｍ、ｄ９０：２１．１μｍ、比表面積：９．９ｍ２／ｇ、タップ密度：０．４４ｇ／ｃｍ３、ラマンＲ値：０．２８）８８．５質量％及び粒子（Ｂ－１）１１．５質量％を混合し、そこに造粒剤を添加し、撹拌造粒機によって撹拌混合した。得られた混合物をハイブリダイゼーションシステムに投入し、ローター周速度８５ｍ／秒の条件で５分間、機械的作用による造粒球形化処理を行った。その後、熱処理により造粒剤を除去し、球形化複合粒子を得た。
　得られた球形化複合粒子とピッチ（灰分：０．０２質量％、金属不純物含有率：２０質量ｐｐｍ、Ｑｉ：１質量％）とを混合し、不活性ガス中で１０００℃で熱処理を行い、焼成物を得た。得られた焼成物を、解砕・分級し、黒鉛（Ａ－１）と粒子（Ｂ－１）とを含む粒子を得た。
　得られた粒子の評価結果を、表１に示す。 [Example 1]
Scaly graphite (A-1) (volume-based average particle diameter: 11.1 μm, d90: 21.1 μm, specific surface area: 9.9 m 2 /g, tap density: 0.44 g/cm 3 , Raman R value: 0 .28) 88.5% by mass and 11.5% by mass of particles (B-1) were mixed, a granulating agent was added thereto, and the mixture was stirred and mixed using a stirring granulator. The obtained mixture was put into a hybridization system, and subjected to mechanical granulation and spheroidization for 5 minutes at a rotor circumferential speed of 85 m/sec. Thereafter, the granulating agent was removed by heat treatment to obtain spherical composite particles.
The obtained spherical composite particles and pitch (ash content: 0.02 mass %, metal impurity content: 20 mass ppm, Qi: 1 mass %) were mixed and heat treated at 1000 ° C. in an inert gas. A fired product was obtained. The obtained fired product was crushed and classified to obtain particles containing graphite (A-1) and particles (B-1).
Table 1 shows the evaluation results of the obtained particles.
　［実施例２］
　粒子（Ｂ－１）を、粒子（Ｂ－２）に変更したこと以外は、実施例１と同様に操作を行い、黒鉛（Ａ－１）と粒子（Ｂ－２）とを含む粒子を得た。
　得られた粒子の評価結果を、表１に示す。 [Example 2]
Particles containing graphite (A-1) and particles (B-2) were obtained by performing the same operation as in Example 1, except that particles (B-1) were changed to particles (B-2). Ta.
Table 1 shows the evaluation results of the obtained particles.
　［比較例１］
　粒子（Ｂ－１）を、粒子（Ｂ１－１）に変更したこと以外は、実施例１と同様に操作を行い、黒鉛（Ａ－１）と粒子（Ｂ１－１）とを含む粒子を得た。
　得られた粒子の評価結果を、表１に示す。 [Comparative example 1]
Particles containing graphite (A-1) and particles (B1-1) were obtained by performing the same operation as in Example 1, except that particles (B-1) were changed to particles (B1-1). Ta.
Table 1 shows the evaluation results of the obtained particles.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１からも分かるように、実施例１～２は、比較例１に対し、負極の初期容量の大きな低下は確認されず、１０サイクル目の容量維持率と充放電効率の改善が確認できた。これは、粒子（Ｂ）に含まれるタンタル酸化物が、容量に影響を与えずに、電解液の分解反応を抑制したためであると考えられる。 As can be seen from Table 1, in Examples 1 and 2, compared to Comparative Example 1, no significant decrease in the initial capacity of the negative electrode was confirmed, and improvements in the capacity retention rate and charge/discharge efficiency at the 10th cycle were confirmed. . This is considered to be because the tantalum oxide contained in the particles (B) suppressed the decomposition reaction of the electrolytic solution without affecting the capacity.
　［実施例３］
　酢酸１．６質量部とエタノール６５．４質量部とを混合した溶液に、セリウム（ＩＶ）エトキシド３．６質量部を加え、２５℃で３０分撹拌後、酢酸８．６質量部とエタノール５１．４質量部とを混合した溶液を滴下し、ジエタノールアミン４．４質量部とエタノール４０質量部とを混合した溶液を滴下し、２５℃で３０分撹拌し、セリウム化合物のゾル溶液を得た。
　ケイ素元素を含む粒子（Ｂ１－１）１００質量部をエタノール１２４．４質量部に分散させた懸濁液に、得られたセリウム化合物のゾル溶液を滴下し、２５℃で６０分撹拌後、６０℃減圧下で溶媒を留去し、粉末を得た。
　得られた粉末を、１２０℃で６時間加熱し、更に、空気雰囲気下で５００℃で１時間加熱した。その後、得られた粉体をメノウで解砕し、ケイ素元素を含む粒子（Ｂ１－１）の表面にセリウム化合物を有する粒子（Ｂ－３）を得た。
　得られた粒子（Ｂ－３）は、ケイ素元素１００質量部に対して、セリウム元素２．２質量部を有するものであり、セリウム化合物が酸化セリウム（ＩＶ）を含むことが確認された。
　得られた粒子（Ｂ－３）の評価結果を、表２に示す。 [Example 3]
3.6 parts by mass of cerium (IV) ethoxide was added to a solution of 1.6 parts by mass of acetic acid and 65.4 parts by mass of ethanol, and after stirring at 25°C for 30 minutes, 8.6 parts by mass of acetic acid and 51 parts by mass of ethanol were added. A solution containing 4.4 parts by mass of diethanolamine and 40 parts by mass of ethanol was added dropwise, and the mixture was stirred at 25° C. for 30 minutes to obtain a sol solution of a cerium compound.
The obtained cerium compound sol solution was added dropwise to a suspension of 100 parts by mass of particles (B1-1) containing silicon element dispersed in 124.4 parts by mass of ethanol, and after stirring at 25°C for 60 minutes, The solvent was distilled off under reduced pressure at °C to obtain a powder.
The obtained powder was heated at 120°C for 6 hours and further heated at 500°C for 1 hour in an air atmosphere. Thereafter, the obtained powder was crushed with an agate to obtain particles (B-3) having a cerium compound on the surface of particles (B1-1) containing silicon element.
The obtained particles (B-3) contained 2.2 parts by mass of cerium element per 100 parts by mass of silicon element, and it was confirmed that the cerium compound contained cerium (IV) oxide.
The evaluation results of the obtained particles (B-3) are shown in Table 2.
　［実施例４］
　空気雰囲気下で５００℃で１時間加熱したことを、窒素雰囲気下で５００℃で１時間加熱したことに変更したこと以外は、実施例１と同様に操作を行い、粒子（Ｂ－４）を得た。
　得られた粒子（Ｂ－４）は、ケイ素元素１００質量部に対して、セリウム元素２．１質量部を有するものであり、セリウム化合物が酸化セリウム（ＩＶ）を含むことが確認された。
　得られた粒子の評価結果を、表２に示す。 [Example 4]
Particles (B-4) were prepared in the same manner as in Example 1, except that heating at 500°C for 1 hour in an air atmosphere was changed to heating at 500°C for 1 hour in a nitrogen atmosphere. Obtained.
The obtained particles (B-4) contained 2.1 parts by mass of cerium element per 100 parts by mass of silicon element, and it was confirmed that the cerium compound contained cerium (IV) oxide.
Table 2 shows the evaluation results of the obtained particles.
　［実施例５］
　セリウム（ＩＶ）エトキシド３．６質量部を７．２質量部に変更したこと以外は、実施例４と同様に操作を行い、粒子（Ｂ－５）を得た。
　得られた粒子（Ｂ－５）は、ケイ素元素１００質量部に対して、セリウム元素４．２質量部を有するものであり、セリウム化合物が酸化セリウム（ＩＶ）を含むことが確認された。
　得られた粒子の評価結果を、表２に示す。 [Example 5]
Particles (B-5) were obtained in the same manner as in Example 4, except that 3.6 parts by mass of cerium (IV) ethoxide was changed to 7.2 parts by mass.
The obtained particles (B-5) contained 4.2 parts by mass of cerium element per 100 parts by mass of silicon element, and it was confirmed that the cerium compound contained cerium (IV) oxide.
Table 2 shows the evaluation results of the obtained particles.
　［比較例２］
　ケイ素元素を含む粒子（Ｂ１－１）をそのまま用い、ケイ素元素を含む粒子（Ｂ１－１）の評価結果を、表２に示す。 [Comparative example 2]
The particles containing silicon element (B1-1) were used as they were, and Table 2 shows the evaluation results for the particles containing silicon element (B1-1).
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　［実施例６］
　鱗片状黒鉛（Ａ－１）（体積基準平均粒径：１１．１μｍ、ｄ９０：２１．１μｍ、比表面積：９．９ｍ２／ｇ、タップ密度：０．４４ｇ／ｃｍ３、ラマンＲ値：０．２８）８８．５質量％及び実施例３で得られた粒子（Ｂ－３）１１．５質量％を混合し、そこに造粒剤を添加し、撹拌造粒機によって撹拌混合した。得られた混合物をハイブリダイゼーションシステムに投入し、ローター周速度８５ｍ／秒の条件で５分間、機械的作用による造粒球形化処理を行った。その後、熱処理により造粒剤を除去し、球形化複合粒子を得た。
　得られた球形化複合粒子とピッチ（灰分：０．０２質量％、金属不純物含有率：２０質量ｐｐｍ、Ｑｉ：１質量％）とを混合し、不活性ガス中で１０００℃で熱処理を行い、焼成物を得た。得られた焼成物を、解砕・分級し、黒鉛（Ａ－１）と粒子（Ｂ－３）とを含む粒子を得た。
　得られた粒子の評価結果を、表３に示す。 [Example 6]
Scaly graphite (A-1) (volume-based average particle diameter: 11.1 μm, d90: 21.1 μm, specific surface area: 9.9 m 2 /g, tap density: 0.44 g/cm 3 , Raman R value: 0 .28) 88.5% by mass and 11.5% by mass of particles (B-3) obtained in Example 3 were mixed, a granulating agent was added thereto, and the mixture was stirred and mixed using a stirring granulator. The obtained mixture was put into a hybridization system, and subjected to mechanical granulation and spheroidization for 5 minutes at a rotor circumferential speed of 85 m/sec. Thereafter, the granulating agent was removed by heat treatment to obtain spherical composite particles.
The obtained spherical composite particles and pitch (ash content: 0.02 mass %, metal impurity content: 20 mass ppm, Qi: 1 mass %) were mixed and heat treated at 1000 ° C. in an inert gas. A fired product was obtained. The obtained fired product was crushed and classified to obtain particles containing graphite (A-1) and particles (B-3).
Table 3 shows the evaluation results of the obtained particles.
　［比較例３］
　粒子（Ｂ－３）を、粒子（Ｂ１－１）に変更したこと以外は、実施例６と同様に操作を行い、黒鉛（Ａ－１）と粒子（Ｂ１－１）とを含む粒子を得た。
　得られた粒子の評価結果を、表３に示す。 [Comparative example 3]
Particles containing graphite (A-1) and particles (B1-1) were obtained by performing the same operation as in Example 6, except that particles (B-3) were changed to particles (B1-1). Ta.
Table 3 shows the evaluation results of the obtained particles.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表２からも分かるように、実施例３～５は、比較例２に対し、負極の初期容量の大きな低下は確認されず、２５サイクル目の容量維持率の改善が確認できた。
　表３からも分かるように、実施例６は、比較例３に対し、負極の初期容量の大きな低下は確認されず、１０サイクル目の容量維持率と充放電効率の改善が確認できた。これは、粒子（Ｂ）が有するセリウム化合物が、容量に影響を与えずに、電解液の分解反応を抑制したためであると考えられる。 As can be seen from Table 2, in Examples 3 to 5, compared to Comparative Example 2, no significant decrease in the initial capacity of the negative electrode was observed, and an improvement in the capacity retention rate at the 25th cycle was confirmed.
As can be seen from Table 3, in Example 6, compared to Comparative Example 3, no significant decrease in the initial capacity of the negative electrode was observed, and improvements in the capacity retention rate and charge/discharge efficiency at the 10th cycle were confirmed. This is considered to be because the cerium compound contained in the particles (B) suppressed the decomposition reaction of the electrolytic solution without affecting the capacity.
　本発明を特定の態様を用いて詳細に説明したが、本発明の意図と範囲を離れることなく様々な変更が可能であることは当業者に明らかである。
　本出願は、２０２２年３月２２日付で出願された日本特許出願２０２２－０４５５８０及び日本特許出願２０２２－０４５５８１に基づいており、その全体が引用により援用される。 Although the invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various changes can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2022-045580 and Japanese Patent Application No. 2022-045581 filed on March 22, 2022, which are incorporated by reference in their entirety.
　本発明の粒子は、二次電池の負極材としてサイクル特性に優れた二次電池を提供することができることから、二次電池の負極の活物質として好適に用いることができ、非水系二次電池の負極の活物質としてより好適に用いることができ、リチウムイオン二次電池の負極の活物質として特に好適に用いることができる。

  Since the particles of the present invention can provide a secondary battery with excellent cycle characteristics as a negative electrode material for a secondary battery, they can be suitably used as an active material for a negative electrode of a secondary battery, and can be used for non-aqueous secondary batteries. It can be more suitably used as an active material for a negative electrode of a lithium ion secondary battery, and can be particularly suitably used as an active material for a negative electrode of a lithium ion secondary battery.

Claims (16)

  1. 　黒鉛（Ａ）と、タンタル化合物及びセリウム化合物からなる群より選ばれる少なくとも１種を含む粒子（Ｂ）と、を含む粒子であって、
    　粒子（Ｂ）が黒鉛（Ａ）に内包されたものである、粒子。     Particles containing graphite (A) and particles (B) containing at least one selected from the group consisting of tantalum compounds and cerium compounds,
    Particles in which particles (B) are encapsulated in graphite (A).
  2. 　黒鉛（Ａ）のラマンＲ値が、０．１～０．７である、請求項１に記載の粒子。 The particles according to claim 1, wherein the graphite (A) has a Raman R value of 0.1 to 0.7.
  3. 　粒子（Ｂ）が、更に、ケイ素元素を含む、請求項１又は２に記載の粒子。 The particle according to claim 1 or 2, wherein the particle (B) further contains silicon element.
  4. 　粒子（Ｂ）が、ケイ素元素を含む粒子（Ｂ１）の表面にタンタル化合物及びセリウム化合物からなる群より選ばれる少なくとも１種が被覆されたものである、請求項２に記載の粒子。 The particle according to claim 2, wherein the particle (B) is a particle (B1) containing silicon element whose surface is coated with at least one selected from the group consisting of a tantalum compound and a cerium compound.
  5. 　タンタル化合物が、五酸化タンタルを含む、請求項１～４のいずれか１項に記載の粒子。 The particles according to any one of claims 1 to 4, wherein the tantalum compound contains tantalum pentoxide.
  6. 　セリウム化合物が、酸化セリウム（ＩＶ）を含む、請求項１～５のいずれか１項に記載の粒子。 The particles according to any one of claims 1 to 5, wherein the cerium compound contains cerium (IV) oxide.
  7. 　粒子（Ｂ）の体積基準平均粒径が、０．２μｍ～０．８μｍである、請求項１～６のいずれか１項に記載の粒子。 The particles according to any one of claims 1 to 6, wherein the particles (B) have a volume-based average particle diameter of 0.2 μm to 0.8 μm.
  8. 　表面に炭素質物を有する、請求項１～７のいずれか１項に記載の粒子。 The particle according to any one of claims 1 to 7, having a carbonaceous material on the surface.
  9. 　黒鉛（Ａ）と粒子（Ｂ）の合計１００質量％中、黒鉛（Ａ）の含有率が６０質量％～９５質量％であり、粒子（Ｂ）の含有率が５質量％～４０質量％である、請求項１～８のいずれか１項に記載の粒子。 Of the total 100% by mass of graphite (A) and particles (B), the content of graphite (A) is 60% by mass to 95% by mass, and the content of particles (B) is 5% by mass to 40% by mass. Particles according to any one of claims 1 to 8.
  10. 　黒鉛（Ａ）に、タンタル化合物及びセリウム化合物からなる群より選ばれる少なくとも１種を含む粒子（Ｂ）を内包する工程を含む、粒子の製造方法。 A method for producing particles, comprising a step of encapsulating particles (B) containing at least one selected from the group consisting of tantalum compounds and cerium compounds in graphite (A).
  11. 　黒鉛（Ａ）のラマンＲ値が、０．１～０．７である、請求項１０に記載の粒子の製造方法。 The method for producing particles according to claim 10, wherein the graphite (A) has a Raman R value of 0.1 to 0.7.
  12. 　更に、ケイ素元素を含む粒子（Ｂ１）の表面にタンタル化合物及びセリウム化合物からなる群より選ばれる少なくとも１種を被覆する工程を含む、請求項１０又は１１に記載の粒子の製造方法。 The method for producing particles according to claim 10 or 11, further comprising the step of coating the surface of the particles (B1) containing silicon element with at least one selected from the group consisting of tantalum compounds and cerium compounds.
  13. 　セリウム化合物を含む粒子（Ｂ）を含む粒子であって、ケイ素元素を含む粒子（Ｂ１）の表面にセリウム化合物が被覆されたものである、粒子。 A particle containing a particle (B) containing a cerium compound, which is a particle containing a silicon element (B1) whose surface is coated with a cerium compound.
  14. 　粒子（Ｂ）の体積基準平均粒径が、０．２μｍ～０．８μｍである、請求項１３に記載の粒子。 The particles according to claim 13, wherein the particles (B) have a volume-based average particle diameter of 0.2 μm to 0.8 μm.
  15. 　集電体上に、請求項１～９、１３～１４のいずれか１項に記載の粒子を塗布する工程を含む、負極の製造方法。 A method for producing a negative electrode, comprising the step of applying the particles according to any one of claims 1 to 9 and 13 to 14 onto a current collector.
  16. 　正極、負極及び電解質を含む二次電池の製造方法であって、
    　負極が、請求項１５に記載の製造方法により得られたものである、二次電池の製造方法。

          A method for manufacturing a secondary battery including a positive electrode, a negative electrode, and an electrolyte, the method comprising:
    A method for manufacturing a secondary battery, wherein the negative electrode is obtained by the manufacturing method according to claim 15.
PCT/JP2023/003531 2022-03-22 2023-02-03 Particles, method for manufacturing particles, method for manufacturing negative electrode, and method for manufacturing secondary battery WO2023181659A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005071938A (en) * 2003-08-27 2005-03-17 Nec Corp Negative electrode activator for secondary battery, negative electrode and secondary battery using the same, and manufacturing method of negative electrode activator for secondary battery and negative electrode for secondary battery using the activator
JP2011096455A (en) * 2009-10-28 2011-05-12 Shin-Etsu Chemical Co Ltd Negative electrode material for non-aqueous electrolyte secondary battery, method of manufacturing the same, and lithium-ion secondary battery
JP2015125817A (en) * 2013-12-25 2015-07-06 株式会社豊田自動織機 Composite negative electrode active material body, negative electrode for nonaqueous electrolyte secondary batteries, and nonaqueous electrolyte secondary battery
JP2020205425A (en) * 2017-10-27 2020-12-24 バーサム マテリアルズ ユーエス，リミティド ライアビリティ カンパニー Composite particles, method of refining the same, and use thereof
WO2021241750A1 (en) * 2020-05-28 2021-12-02 昭和電工株式会社 Composite particles, negative electrode material, and lithium ion secondary battery

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005071938A (en) * 2003-08-27 2005-03-17 Nec Corp Negative electrode activator for secondary battery, negative electrode and secondary battery using the same, and manufacturing method of negative electrode activator for secondary battery and negative electrode for secondary battery using the activator
JP2011096455A (en) * 2009-10-28 2011-05-12 Shin-Etsu Chemical Co Ltd Negative electrode material for non-aqueous electrolyte secondary battery, method of manufacturing the same, and lithium-ion secondary battery
JP2015125817A (en) * 2013-12-25 2015-07-06 株式会社豊田自動織機 Composite negative electrode active material body, negative electrode for nonaqueous electrolyte secondary batteries, and nonaqueous electrolyte secondary battery
JP2020205425A (en) * 2017-10-27 2020-12-24 バーサム マテリアルズ ユーエス，リミティド ライアビリティ カンパニー Composite particles, method of refining the same, and use thereof
WO2021241750A1 (en) * 2020-05-28 2021-12-02 昭和電工株式会社 Composite particles, negative electrode material, and lithium ion secondary battery

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